# lgrenc.def

LGR Greek font encoding definitions

Copyright
  © 2010, 2014 Günter Milde
Licence

  This work may be distributed and/or modified under the conditions of the LaTeX Project Public License, either version 1.3 of this license or any later version.

Abstract

The LGR font encoding is the de-facto standard for Greek typesetting with LaTeX. This file provides a comprehensive set of macros to typeset Greek with LGR encoded fonts. It works for both, monotonic and polytonic Greek, independent of the babel package.

Contents

- Changelog

- Usage

- Implementation

  - Read this file only once

  - Identification

  - Base setup

  - Text symbols

    - Greek Alphabet

    - Additional Greek symbols

      - Ancient Greek Numbers (Athenian Numerals)

      - Archaic letters

      - Numeral signs

      - variant symbols

    - Other

    - Not implemented

  - Diacritics

    - Named macros

    - Aliases

  - Common Greek font encoding definitions

  - Composite definitions

    - Composite diacritics

    - Pre-composed letters

      - Small letters with diacritics

      - Capital letters with diacritics

  - UPPERCASE

# Changelog

Development of this file started under the name “lgrxenc.def” as part of the lgrx bundle. With version 0.8, it moved to greek-fontenc/lgrx.def.

0.1 | 2010-03-31 | initial attempt
0.2 | 2010-04-20 | diacritics dropped in UPPERCASE.
0.3 | 2010-06-08 | handle Titlecase and UPPERCASE extending \@uclclist.
0.4 | 2010-06-15 | more text symbols.
0.5 | 2010-08-27 | support \textalpha … \textOmega.
0.5.1 | 2012-05-08 | upload to CTAN.
0.6 | 2012-06-29 | \TextGreek wrapper command,
|  | aliases for puenc.def compatibility.
0.6.1 | 2013-02-12 | \@uclclist entries for PU aliases.
0.7 | 2013-05-13 | documentation update, new accent macros names,
|  | \TextGreek renamed to \ensuregreek.
0.8 | 2013-05-13 | rename to lgrenc.def (superseding the babel version),
|  | move to greek-fontenc,
|  | drop the old (<0.7) internal accent macros names.
0.8.1 | 2013-05-22 | auxiliary macro update@uclc@with@greek,
|  | conservative naming: “text” prefix for archaic letters,
|  | “LGR@” prefix for internal commands,
|  | remove not required alias macros.
0.8.2 | 2013-05-23 | fix name: \textpentehkaton -> \textpentehekaton,
|  | fix \textperiodcentered,
|  | add composite command for Ῥ (Rho with Dasia).
0.9 | 2013-07-16 | move common definitions to greek-fontenc.def,
|  | add composite commands for single quotation marks.
0.11.2 | 2014-09-04 | remove duplicate code.
0.13 | 2015-08-04 | Support for symbol variants.
0.13.1 | 2015-12-07 | Fix rho with dasia bug (Linus Romer).
0.13.3 | 2019-07-09 | Drop error font declaration (cf. ltxbugs 4399).

# Usage

Load this file by calling fontenc with the LGR option or indirectly via the babel, textalpha or alphabeta packages.

Example:

  Select font encodings T1 (as default) and LGR (for Greek):

  > \usepackage[LGR,T1]{fontenc}

# Implementation

## Read this file only once

Note

The use of \@ifundefined has the side-effect that the tested macro becomes defined and set to \relax (polluting the namespace and interfering with tests via eTeX’s \ifdefined). However, in this case no harm is done as the macro is defined by the identification below anyway.

    % read this file only once
    \@ifundefined{ver@lgrenc.def}
      {}
      {\message{LGR font encoding definitions already loaded}
       \expandafter\endinput % "return"
      }

## Identification

    \ProvidesFile{lgrenc.def}
    [2019/07/09 v0.13.3 LGR Greek font encoding definitions]
    % Copyright © 2010 Günter Milde
    % This file is part of the "greek-fontenc" package.
    % It may be distributed and/or modified under the
    % conditions of the "LaTeX Project Public License", either
    % version 1.3 of this license or any later version.

You can test the version date using

    \@ifl@ter {extension}{filename}{date}{YES}{NO}

or using ltxcmds’ \@iffilelater.

## Base setup

Declare the LGR font encoding and base substitutions:

    \DeclareFontEncoding{LGR}{}{}
    \DeclareFontSubstitution{LGR}{cmr}{m}{n}

## Text symbols

### Greek Alphabet

Greek letters are accessible by the Latin transcription, but the mapping is specific to the LGR font encoding.

The LICR macros provide a way to access the symbols independent of the specific font encoding, in any font encoding supporting Greek. An alternative Greek font encodings is LGI (ibycus). Greek script is also supported by the Unicode-based font encodings PU (PDF Unicode used by hyperref for PDF metadata), TU, EU1 (XeTeX) and EU2 (LuaTeX). The textalpha package makes these macros available independent of the current font encoding.

    \DeclareTextSymbol{\textAlpha}{LGR}{65}
    \DeclareTextSymbol{\textBeta}{LGR}{66}
    \DeclareTextSymbol{\textGamma}{LGR}{71}
    \DeclareTextSymbol{\textDelta}{LGR}{68}
    \DeclareTextSymbol{\textEpsilon}{LGR}{69}
    \DeclareTextSymbol{\textZeta}{LGR}{90}
    \DeclareTextSymbol{\textEta}{LGR}{72}
    \DeclareTextSymbol{\textTheta}{LGR}{74}
    \DeclareTextSymbol{\textIota}{LGR}{73}
    \DeclareTextSymbol{\textKappa}{LGR}{75}
    \DeclareTextSymbol{\textLambda}{LGR}{76}
    \DeclareTextSymbol{\textMu}{LGR}{77}
    \DeclareTextSymbol{\textNu}{LGR}{78}
    \DeclareTextSymbol{\textXi}{LGR}{88}
    \DeclareTextSymbol{\textOmicron}{LGR}{79}
    \DeclareTextSymbol{\textPi}{LGR}{80}
    \DeclareTextSymbol{\textRho}{LGR}{82}
    \DeclareTextSymbol{\textSigma}{LGR}{83}
    \DeclareTextSymbol{\textTau}{LGR}{84}
    \DeclareTextSymbol{\textUpsilon}{LGR}{85}
    \DeclareTextSymbol{\textPhi}{LGR}{70}
    \DeclareTextSymbol{\textChi}{LGR}{81}
    \DeclareTextSymbol{\textPsi}{LGR}{89}
    \DeclareTextSymbol{\textOmega}{LGR}{87}
    %
    \DeclareTextSymbol{\textalpha}{LGR}{97}
    \DeclareTextSymbol{\textbeta}{LGR}{98}
    \DeclareTextSymbol{\textgamma}{LGR}{103}
    \DeclareTextSymbol{\textdelta}{LGR}{100}
    \DeclareTextSymbol{\textepsilon}{LGR}{101}
    \DeclareTextSymbol{\textzeta}{LGR}{122}
    \DeclareTextSymbol{\texteta}{LGR}{104}
    \DeclareTextSymbol{\texttheta}{LGR}{106}
    \DeclareTextSymbol{\textiota}{LGR}{105}
    \DeclareTextSymbol{\textkappa}{LGR}{107}
    \DeclareTextSymbol{\textlambda}{LGR}{108}
    \DeclareTextSymbol{\textmu}{LGR}{109}
    \DeclareTextSymbol{\textnu}{LGR}{110}
    \DeclareTextSymbol{\textxi}{LGR}{120}
    \DeclareTextSymbol{\textomicron}{LGR}{111}
    \DeclareTextSymbol{\textpi}{LGR}{112}
    \DeclareTextSymbol{\textrho}{LGR}{114}
    \DeclareTextCommand{\textsigma}{LGR}{s\noboundary} % σ
    \DeclareTextSymbol{\textvarsigma}{LGR}{99}         % ς final sigma
    \DeclareTextCommand{\textfinalsigma}{LGR}{\textvarsigma} % ς final sigma
    \DeclareTextSymbol{\textautosigma}{LGR}{115}       % σ (ς at end of word)
    \DeclareTextSymbol{\texttau}{LGR}{116}
    \DeclareTextSymbol{\textupsilon}{LGR}{117}
    \DeclareTextSymbol{\textphi}{LGR}{102}
    \DeclareTextSymbol{\textchi}{LGR}{113}
    \DeclareTextSymbol{\textpsi}{LGR}{121}
    \DeclareTextSymbol{\textomega}{LGR}{119}

### Additional Greek symbols

#### Ancient Greek Numbers (Athenian Numerals)

Names from ucs (ucsencs.def) (In ucs, five hundred is (wrongly?) named textpentehkaton.)

    \DeclareTextSymbol{\textpentedeka}{LGR}{2}    % GREEK ACROPHONIC ATTIC FIFTY
    \DeclareTextSymbol{\textpentehekaton}{LGR}{3} % GREEK ACROPHONIC ATTIC FIVE HUNDRED
    \DeclareTextSymbol{\textpenteqilioi}{LGR}{4}  % GREEK ACROPHONIC ATTIC FIVE THOUSAND
    \DeclareTextSymbol{\textpentemuria}{LGR}{5}  % GREEK ACROPHONIC ATTIC FIFTY THOUSAND

#### Archaic letters

Names after teubner and ucs:

    \DeclareTextSymbol{\textstigma}{LGR}{6}       % ϛ
    \DeclareTextSymbol{\textvarstigma}{LGR}{7}    % stigma variant (CB.enc, teubner)
    \DeclareTextSymbol{\textkoppa}{LGR}{18}       % ϟ (greek small letter koppa)
    \DeclareTextSymbol{\textqoppa}{LGR}{19}       % ϙ (archaic koppa)
    \DeclareTextSymbol{\textQoppa}{LGR}{21}       % Ϙ (archaic Koppa)
    \DeclareTextSymbol{\textStigma}{LGR}{22}      % Ϛ in some fonts ϹΤ ligature
    \DeclareTextSymbol{\textSampi}{LGR}{23}       % Ϡ
    \DeclareTextSymbol{\textsampi}{LGR}{27}       % ϡ
    \DeclareTextSymbol{\textanoteleia}{LGR}{38}   % ·
    \DeclareTextSymbol{\texterotimatiko}{LGR}{63} % ;
    \DeclareTextSymbol{\textdigamma}{LGR}{147}    % ϝ (ucs) \digamma used by amsmath for math-macro
    \DeclareTextSymbol{\textDigamma}{LGR}{195}    % Ϝ (ucs)

#### Numeral signs

See also http://en.wikipedia.org/wiki/Greek_numerals

Names from ucs:

    \DeclareTextSymbol{\textdexiakeraia}{LGR}{254}      % ʹ (Dexia keraia)
    \DeclareTextSymbol{\textaristerikeraia}{LGR}{255}   % ͵ (Aristeri keraia)

#### variant symbols

Mathematical notation distinguishes variant shapes for pi, phi, rho, theta (small and capital), beta, and kappa (characters for the latter three symbols are not included in TeX’s math fonts). These variations have no syntactic meaning in Greek text and are not given code-points in the LGR encoding. Greek text fonts use the shape variants interchangeabely.

However, as Unicode defines separate code points for the symbol variants, we provide fallback LICR macros with detailed error reporting:

    \providecommand*{\LGR@TextSymbolUnavailable}[1]{%
      \PackageError{greek-fontenc}{character \string#1 not available \MessageBreak
        in 8-bit TeX}
        {Use XeTeX/LuaTeX if you need to distinguish the symbol from the letter.\MessageBreak
         The package `textalpha' with `normalize-symbols' maps the GREEK SYMBOL\MessageBreak
         character to the corresponding GREEK LETTER.\MessageBreak
         Press <return> to proceed (dropping the symbol from the document).}
    }

    \providecommand*{\LGR@TextSymbolOnlyMath}[2]{%
      \PackageError{greek-fontenc}{character \string#1 not available in text mode}
        {Use #2 or XeTeX/LuaTeX if you need to distinguish\MessageBreak
         the symbol from the letter.\MessageBreak
         The package `textalpha' with `normalize-symbols' maps the GREEK SYMBOL\MessageBreak
         character to the corresponding GREEK LETTER.\MessageBreak
         Press <return> to proceed (dropping the symbol from the document).}
    }

    \ProvideTextCommand{\textbetasymbol} {LGR}{\LGR@TextSymbolUnavailable{ϐ beta symbol}}
    \ProvideTextCommand{\textkappasymbol}{LGR}{\LGR@TextSymbolUnavailable{ϰ kappa symbol}}
    \ProvideTextCommand{\textThetasymbol}{LGR}{\LGR@TextSymbolUnavailable{ϴ Theta symbol}}

    \ProvideTextCommand{\textthetasymbol}  {LGR}{\LGR@TextSymbolOnlyMath{ϑ theta symbol}{$\vartheta$}}
    \ProvideTextCommand{\textphisymbol}    {LGR}{\LGR@TextSymbolOnlyMath{ϕ phi symbol}{$\phi$}}
    \ProvideTextCommand{\textpisymbol}     {LGR}{\LGR@TextSymbolOnlyMath{ϖ pi symbol}{$\varpi$}}
    \ProvideTextCommand{\textrhosymbol}    {LGR}{\LGR@TextSymbolOnlyMath{ϱ rho symbol}{$\varrho$}}
    \ProvideTextCommand{\textepsilonsymbol}{LGR}{\LGR@TextSymbolOnlyMath{ϵ lunate epsilon symbol}{$\epsilon$}}

### Other

Characters that also exist in other font encodings:

- define them for LGR if there is a matching glyph,

- use established macro names that match with other *enc.def files and textcomp.sty.

All encodings: See usrguide.pdf, chapter 3.14 ff:

    \DeclareTextSymbol{\textendash}{LGR}{0}          % EN DASH
    \DeclareTextSymbol{\textquoteleft}{LGR}{28}      % ‘
    \DeclareTextSymbol{\textquoteright}{LGR}{29}     % ’
    \DeclareTextSymbol{\textperiodcentered}{LGR}{38} % · = \textanoteleia
    \DeclareTextSymbol{\textcompwordmark}{LGR}{118}  % ZERO WIDTH NO JOINER
    \DeclareTextSymbol{\textemdash}{LGR}{127}        % EM DASH

T1:

    \DeclareTextSymbol{\guillemotleft}{LGR}{123}     % «
    \DeclareTextSymbol{\guillemotright}{LGR}{125}    % »

TS1:

    \ProvideTextCommand{\textasciibreve}{LGR}{\char30\textcompwordmark}  % ˘
    \ProvideTextCommand{\textasciimacron}{LGR}{\char31\textcompwordmark} % ¯
    \ProvideTextCommand{\textasciidieresis}{LGR}{"\textcompwordmark}     % "
    \ProvideTextCommand{\textasciiacute}{LGR}{'\textcompwordmark}        % '
    \ProvideTextCommand{\textasciigrave}{LGR}{`\textcompwordmark}        % `
    \DeclareTextCommand{\textasciitilde}{LGR}{\char126\textcompwordmark} % ~
    \DeclareTextSymbol{\textohm}{LGR}{87}            % Ω (Ohm sign -> Omega)
    \DeclareTextSymbol{\texteuro}{LGR}{24}           % € \euro in greek.ldf
    \DeclareTextSymbol{\textpercent}{LGR}{37}        % %
    \DeclareTextSymbol{\textperthousand}{LGR}{25}    % ‰ \permill in greek.ldf

T3 (tipa):

    \DeclareTextSymbol{\textschwa}{LGR}{26}          % ə

T3 also defines some greek letters as well as Latin characters with Greek names:

According to the Unicode standard, the following IPA characters are identic to the Greek letters:

- 03B2 greek small letter beta

- 03B8 greek small letter theta

- 03BB greek small letter lamda

- 03C7 greek small letter chi

The following characters in the IPA block refer to Greek letters:

- 0251 LATIN SMALL LETTER ALPHA → greek small letter alpha - 03B1

- 025B LATIN SMALL LETTER OPEN E = epsilon → greek small letter epsilon - 03B5

- 0263 LATIN SMALL LETTER GAMMA → greek small letter gamma - 03B3

- 0269 LATIN SMALL LETTER IOTA → greek small letter iota - 03B9

- 0278 LATIN SMALL LETTER PHI → greek small letter phi - 03C6

- 028A LATIN SMALL LETTER UPSILON → greek small letter upsilon - 03C5

tipa uses the macro names \textepsilon, \textgamma, \textiota, \textphi, and \textupsilon for the Latin characters. This is no problem with 8-bit fonts (set the font encoding to T3 vs. LGR to disambiguate), but leads to ambiguity with Unicode fonts. xunicode uses the gr infix and alias names to disambiguate:

- 03B3 \textgrgamma

- 03B9 \textgriota

- 03C6 \textgrphi (see x0278 )

but not for epsilon and upsilon (03C2 \textgrsigma is the final sigma).

It also assigns alias names to the Latin counterparts, however not on a systematical basis:

- 0194 \textGammaafrican

- 0196 \textIotaafrican

- 0251 \textscripta

- 025B \texteopen

- 0263 \textbabygamma, \textgammalatinsmall

- 0269 \textiotalatin

- 028A \textscupsilon % TIPA-U

### Not implemented

The characters at position 16 and 17 are used in the \nexus macro of the teubner package to form an extensible, hat-like bracket. In CB.enc, they are mapped to

> 16–MODIFIER LETTER LOW ACUTE ACCENT 17–MODIFIER LETTER LOW GRAVE ACCENT

but according to the documentation of Werner Lemberg’s babel patch, they rather represent the left and right part of U+23E0 TOP TORTOISE SHELL BRACKET.

Babel’s lgrenc.def has some definitions to prevent surprises with macros that expect a Latin script. These definitions are problematic in a font-encoding definition file as they require \textlatin which is defined in babel.def. They were moved to greek.ldf.

## Diacritics

This section defines named macros for Greek diacritics and standard symbol macros as alias for simple diacritics. Convenient input conventions for composite diacritics are defined as composite definitions.

Advantages:

- input convention similar to LGR input encodings (just prepend a \).

- Access pre-composed characters without resorting to the ligature mechanism (allows proper kerning, cf. teubner-doc).

- Named macros can be used to ensure a font encoding supporting Greek is used. However, substitution with pre-composed characters works only for the active font encoding (cf. textalpha). Named accent macros can also be used instead of the \@tabacckludge by to-LaTeX converters to ensure working also inside the tabbing environment.

- Named macros are required for upcasing according to Greek typesetting conventions (cf. UPPERCASE below) and for composite diacritics.

### Named macros

Definitions are based on the teubner package by Claudio Beccari, the ucs package, and the babel patch by Werner Lemberg. Names are derived from the Unicode name with the prefix “acc” (cf. How to name accent macros? in the README) reducing the probability of incompatibilities compared to the two-letter teubner diacritic macros or the “text” prefix used by ucs.

Simple Greek diacritics:

    \DeclareTextAccent{\accdialytika}{LGR}{34} % διαλυτικά (diaeresis/trema)
    \DeclareTextAccent{\acctonos}{LGR}{39} % τόνος/ὀξεῖα tonos/oxia (acute)
    \DeclareTextAccent{\accdasia}{LGR}{60} % δασεῖα spiritus asper (rough breathing)
    \DeclareTextAccent{\accpsili}{LGR}{62} % ψιλή spiritus lenis (smooth breathing)
    \DeclareTextAccent{\accvaria}{LGR}{96} % βαρεῖα (grave)
    \DeclareTextAccent{\accperispomeni}{LGR}{126} % περισπωμένη (circonflex/tilde)

The sub-iota is input after the base character. In LGR fonts, ligatures are defined for pre-composed characters, the postfix ligature does not interfere with kerning:

    \DeclareTextSymbol{\prosgegrammeni}{LGR}{8}  % ι "capital" sub-iota
    \DeclareTextSymbol{\ypogegrammeni}{LGR}{124} % ͺ "small" sub-iota

Composite diacritics:

    %                                                       Teubner name
    \DeclareTextAccent{\accdialytikaperispomeni}{LGR}{32} % Cd
    \DeclareTextAccent{\accdialytikatonos}{LGR}{35}       % Ad
    \DeclareTextAccent{\accdialytikavaria}{LGR}{36}       % Gd

    \DeclareTextAccent{\accdasiaperispomeni}{LGR}{64}     % Cr
    \DeclareTextAccent{\accdasiavaria}{LGR}{67}           % Gr
    \DeclareTextAccent{\accdasiaoxia}{LGR}{86}            % Ar

    \DeclareTextAccent{\accpsiliperispomeni}{LGR}{92}     % Cs
    \DeclareTextAccent{\accpsilioxia}{LGR}{94}            % As
    \DeclareTextAccent{\accpsilivaria}{LGR}{95}           % Gs

For classical Greek and linguistics, the LGR font encoding contains a number of additional diacritic symbols:

    \DeclareTextAccent{\accinvertedbrevebelow}{LGR}{1} % INVERTED BREVE BELOW
    \DeclareTextAccent{\textsubarch}{LGR}{1}      % (tipa)
    \DeclareTextAccent{\accbrevebelow}{LGR}{20}   % BREVE BELOW
    \DeclareTextAccent{\u}{LGR}{30}               % BREVE (Greek vrachy)
    \DeclareTextAccent{\=}{LGR}{31}               % MACRON

### Aliases

The standard symbol macros are exclusively used for Greek diacritics in LGR:

    \DeclareTextCommand{\"}{LGR}{\accdialytika}
    \DeclareTextCommand{\'}{LGR}{\acctonos}
    \DeclareTextCommand{\`}{LGR}{\accvaria}
    \DeclareTextCommand{\~}{LGR}{\accperispomeni}

## Common Greek font encoding definitions

The file greek-fontenc.def contains font encoding definitions that are shared by font encodings providing Greek characters:

    \input{greek-fontenc.def}

## Composite definitions

### Composite diacritics

Composite accents can be input as sequence of simple diacritics (in arbitrary order) via named macro, symbol macro and “transcription characters”, e.g. \accdialytica\accvaria\textalpha, \"\'\textalpha, \"'\textalpha, or \'"\textalpha.

The actual declarations are part of the common Greek font encoding definitions.

### Pre-composed letters

#### Small letters with diacritics

(from teubner with changed names of the composite accents):

    \DeclareTextComposite{\accvaria}{LGR}{a}{128}
    \DeclareTextComposite{\accdasia}{LGR}{a}{129}
    \DeclareTextComposite{\accpsili}{LGR}{a}{130}
    \DeclareTextComposite{\accdasiavaria}{LGR}{a}{131}
    \DeclareTextComposite{\acctonos}{LGR}{a}{136}
    \DeclareTextComposite{\accdasiaoxia}{LGR}{a}{137}
    \DeclareTextComposite{\accpsilioxia}{LGR}{a}{138}
    \DeclareTextComposite{\accpsilivaria}{LGR}{a}{139}
    \DeclareTextComposite{\accperispomeni}{LGR}{a}{144}
    \DeclareTextComposite{\accdasiaperispomeni}{LGR}{a}{145}
    \DeclareTextComposite{\accpsiliperispomeni}{LGR}{a}{146}
    \DeclareTextComposite{\accvaria}{LGR}{h}{152}
    \DeclareTextComposite{\accdasia}{LGR}{h}{153}
    \DeclareTextComposite{\accpsili}{LGR}{h}{154}
    \DeclareTextComposite{\acctonos}{LGR}{h}{160}
    \DeclareTextComposite{\accdasiaoxia}{LGR}{h}{161}
    \DeclareTextComposite{\accpsilioxia}{LGR}{h}{162}
    \DeclareTextComposite{\accdasiavaria}{LGR}{h}{163}
    \DeclareTextComposite{\accperispomeni}{LGR}{h}{168}
    \DeclareTextComposite{\accdasiaperispomeni}{LGR}{h}{169}
    \DeclareTextComposite{\accpsiliperispomeni}{LGR}{h}{170}
    \DeclareTextComposite{\accpsilivaria}{LGR}{h}{171}
    \DeclareTextComposite{\accvaria}{LGR}{w}{176}
    \DeclareTextComposite{\accdasia}{LGR}{w}{177}
    \DeclareTextComposite{\accpsili}{LGR}{w}{178}
    \DeclareTextComposite{\accdasiavaria}{LGR}{w}{179}
    \DeclareTextComposite{\acctonos}{LGR}{w}{184}
    \DeclareTextComposite{\accdasiaoxia}{LGR}{w}{185}
    \DeclareTextComposite{\accpsilioxia}{LGR}{w}{186}
    \DeclareTextComposite{\accpsilivaria}{LGR}{w}{187}
    \DeclareTextComposite{\accperispomeni}{LGR}{w}{192}
    \DeclareTextComposite{\accdasiaperispomeni}{LGR}{w}{193}
    \DeclareTextComposite{\accpsiliperispomeni}{LGR}{w}{194}
    \DeclareTextComposite{\accvaria}{LGR}{i}{200}
    \DeclareTextComposite{\accdasia}{LGR}{i}{201}
    \DeclareTextComposite{\accpsili}{LGR}{i}{202}
    \DeclareTextComposite{\accdasiavaria}{LGR}{i}{203}
    \DeclareTextComposite{\acctonos}{LGR}{i}{208}
    \DeclareTextComposite{\accdasiaoxia}{LGR}{i}{209}
    \DeclareTextComposite{\accpsilioxia}{LGR}{i}{210}
    \DeclareTextComposite{\accpsilivaria}{LGR}{i}{211}
    \DeclareTextComposite{\accperispomeni}{LGR}{i}{216}
    \DeclareTextComposite{\accdasiaperispomeni}{LGR}{i}{217}
    \DeclareTextComposite{\accpsiliperispomeni}{LGR}{i}{218}
    \DeclareTextComposite{\accdialytika}{LGR}{i}{240}
    \DeclareTextComposite{\accdialytikavaria}{LGR}{i}{241}
    \DeclareTextComposite{\accdialytikatonos}{LGR}{i}{242}
    \DeclareTextComposite{\accdialytikaperispomeni}{LGR}{i}{243}
    \DeclareTextComposite{\accvaria}{LGR}{u}{204}
    \DeclareTextComposite{\accdasia}{LGR}{u}{205}
    \DeclareTextComposite{\accpsili}{LGR}{u}{206}
    \DeclareTextComposite{\accdasiavaria}{LGR}{u}{207}
    \DeclareTextComposite{\acctonos}{LGR}{u}{212}
    \DeclareTextComposite{\accdasiaoxia}{LGR}{u}{213}
    \DeclareTextComposite{\accpsilioxia}{LGR}{u}{214}
    \DeclareTextComposite{\accpsilivaria}{LGR}{u}{215}
    \DeclareTextComposite{\accperispomeni}{LGR}{u}{220}
    \DeclareTextComposite{\accdasiaperispomeni}{LGR}{u}{221}
    \DeclareTextComposite{\accpsiliperispomeni}{LGR}{u}{222}
    \DeclareTextComposite{\accdialytika}{LGR}{u}{244}
    \DeclareTextComposite{\accdialytikavaria}{LGR}{u}{245}
    \DeclareTextComposite{\accdialytikatonos}{LGR}{u}{246}
    \DeclareTextComposite{\accdialytikaperispomeni}{LGR}{u}{247}
    \DeclareTextComposite{\accvaria}{LGR}{e}{224}
    \DeclareTextComposite{\accdasia}{LGR}{e}{225}
    \DeclareTextComposite{\accpsili}{LGR}{e}{226}
    \DeclareTextComposite{\accdasiavaria}{LGR}{e}{227}
    \DeclareTextComposite{\acctonos}{LGR}{e}{232}
    \DeclareTextComposite{\accdasiaoxia}{LGR}{e}{233}
    \DeclareTextComposite{\accpsilioxia}{LGR}{e}{234}
    \DeclareTextComposite{\accpsilivaria}{LGR}{e}{235}
    \DeclareTextComposite{\accvaria}{LGR}{o}{228}
    \DeclareTextComposite{\accdasia}{LGR}{o}{229}
    \DeclareTextComposite{\accpsili}{LGR}{o}{230}
    \DeclareTextComposite{\accdasiavaria}{LGR}{o}{231}
    \DeclareTextComposite{\acctonos}{LGR}{o}{236}
    \DeclareTextComposite{\accdasiaoxia}{LGR}{o}{237}
    \DeclareTextComposite{\accpsilioxia}{LGR}{o}{238}
    \DeclareTextComposite{\accpsilivaria}{LGR}{o}{239}
    \DeclareTextComposite{\accdasia}{LGR}{r}{251}
    \DeclareTextComposite{\accpsili}{LGR}{r}{252}

Pre-composed letters with diacritics + LICR macros:

    \DeclareTextComposite{\accvaria}{LGR}{\textalpha}{128}
    \DeclareTextComposite{\accdasia}{LGR}{\textalpha}{129}
    \DeclareTextComposite{\accpsili}{LGR}{\textalpha}{130}
    \DeclareTextComposite{\accdasiavaria}{LGR}{\textalpha}{131}
    \DeclareTextComposite{\acctonos}{LGR}{\textalpha}{136}
    \DeclareTextComposite{\accdasiaoxia}{LGR}{\textalpha}{137}
    \DeclareTextComposite{\accpsilioxia}{LGR}{\textalpha}{138}
    \DeclareTextComposite{\accpsilivaria}{LGR}{\textalpha}{139}
    \DeclareTextComposite{\accperispomeni}{LGR}{\textalpha}{144}
    \DeclareTextComposite{\accdasiaperispomeni}{LGR}{\textalpha}{145}
    \DeclareTextComposite{\accpsiliperispomeni}{LGR}{\textalpha}{146}
    \DeclareTextComposite{\accvaria}{LGR}{\texteta}{152}
    \DeclareTextComposite{\accdasia}{LGR}{\texteta}{153}
    \DeclareTextComposite{\accpsili}{LGR}{\texteta}{154}
    \DeclareTextComposite{\acctonos}{LGR}{\texteta}{160}
    \DeclareTextComposite{\accdasiaoxia}{LGR}{\texteta}{161}
    \DeclareTextComposite{\accpsilioxia}{LGR}{\texteta}{162}
    \DeclareTextComposite{\accdasiavaria}{LGR}{\texteta}{163}
    \DeclareTextComposite{\accperispomeni}{LGR}{\texteta}{168}
    \DeclareTextComposite{\accdasiaperispomeni}{LGR}{\texteta}{169}
    \DeclareTextComposite{\accpsiliperispomeni}{LGR}{\texteta}{170}
    \DeclareTextComposite{\accpsilivaria}{LGR}{\texteta}{171}
    \DeclareTextComposite{\accvaria}{LGR}{\textomega}{176}
    \DeclareTextComposite{\accdasia}{LGR}{\textomega}{177}
    \DeclareTextComposite{\accpsili}{LGR}{\textomega}{178}
    \DeclareTextComposite{\accdasiavaria}{LGR}{\textomega}{179}
    \DeclareTextComposite{\acctonos}{LGR}{\textomega}{184}
    \DeclareTextComposite{\accdasiaoxia}{LGR}{\textomega}{185}
    \DeclareTextComposite{\accpsilioxia}{LGR}{\textomega}{186}
    \DeclareTextComposite{\accpsilivaria}{LGR}{\textomega}{187}
    \DeclareTextComposite{\accperispomeni}{LGR}{\textomega}{192}
    \DeclareTextComposite{\accdasiaperispomeni}{LGR}{\textomega}{193}
    \DeclareTextComposite{\accpsiliperispomeni}{LGR}{\textomega}{194}
    \DeclareTextComposite{\accvaria}{LGR}{\textiota}{200}
    \DeclareTextComposite{\accdasia}{LGR}{\textiota}{201}
    \DeclareTextComposite{\accpsili}{LGR}{\textiota}{202}
    \DeclareTextComposite{\accdasiavaria}{LGR}{\textiota}{203}
    \DeclareTextComposite{\acctonos}{LGR}{\textiota}{208}
    \DeclareTextComposite{\accdasiaoxia}{LGR}{\textiota}{209}
    \DeclareTextComposite{\accpsilioxia}{LGR}{\textiota}{210}
    \DeclareTextComposite{\accpsilivaria}{LGR}{\textiota}{211}
    \DeclareTextComposite{\accperispomeni}{LGR}{\textiota}{216}
    \DeclareTextComposite{\accdasiaperispomeni}{LGR}{\textiota}{217}
    \DeclareTextComposite{\accpsiliperispomeni}{LGR}{\textiota}{218}
    \DeclareTextComposite{\accdialytika}{LGR}{\textiota}{240}
    \DeclareTextComposite{\accdialytikavaria}{LGR}{\textiota}{241}
    \DeclareTextComposite{\accdialytikatonos}{LGR}{\textiota}{242}
    \DeclareTextComposite{\accdialytikaperispomeni}{LGR}{\textiota}{243}
    \DeclareTextComposite{\accvaria}{LGR}{\textupsilon}{204}
    \DeclareTextComposite{\accdasia}{LGR}{\textupsilon}{205}
    \DeclareTextComposite{\accpsili}{LGR}{\textupsilon}{206}
    \DeclareTextComposite{\accdasiavaria}{LGR}{\textupsilon}{207}
    \DeclareTextComposite{\acctonos}{LGR}{\textupsilon}{212}
    \DeclareTextComposite{\accdasiaoxia}{LGR}{\textupsilon}{213}
    \DeclareTextComposite{\accpsilioxia}{LGR}{\textupsilon}{214}
    \DeclareTextComposite{\accpsilivaria}{LGR}{\textupsilon}{215}
    \DeclareTextComposite{\accperispomeni}{LGR}{\textupsilon}{220}
    \DeclareTextComposite{\accdasiaperispomeni}{LGR}{\textupsilon}{221}
    \DeclareTextComposite{\accpsiliperispomeni}{LGR}{\textupsilon}{222}
    \DeclareTextComposite{\accdialytika}{LGR}{\textupsilon}{244}
    \DeclareTextComposite{\accdialytikavaria}{LGR}{\textupsilon}{245}
    \DeclareTextComposite{\accdialytikatonos}{LGR}{\textupsilon}{246}
    \DeclareTextComposite{\accdialytikaperispomeni}{LGR}{\textupsilon}{247}
    \DeclareTextComposite{\accvaria}{LGR}{\textepsilon}{224}
    \DeclareTextComposite{\accdasia}{LGR}{\textepsilon}{225}
    \DeclareTextComposite{\accpsili}{LGR}{\textepsilon}{226}
    \DeclareTextComposite{\accdasiavaria}{LGR}{\textepsilon}{227}
    \DeclareTextComposite{\acctonos}{LGR}{\textepsilon}{232}
    \DeclareTextComposite{\accdasiaoxia}{LGR}{\textepsilon}{233}
    \DeclareTextComposite{\accpsilioxia}{LGR}{\textepsilon}{234}
    \DeclareTextComposite{\accpsilivaria}{LGR}{\textepsilon}{235}
    \DeclareTextComposite{\accvaria}{LGR}{\textomicron}{228}
    \DeclareTextComposite{\accdasia}{LGR}{\textomicron}{229}
    \DeclareTextComposite{\accpsili}{LGR}{\textomicron}{230}
    \DeclareTextComposite{\accdasiavaria}{LGR}{\textomicron}{231}
    \DeclareTextComposite{\acctonos}{LGR}{\textomicron}{236}
    \DeclareTextComposite{\accdasiaoxia}{LGR}{\textomicron}{237}
    \DeclareTextComposite{\accpsilioxia}{LGR}{\textomicron}{238}
    \DeclareTextComposite{\accpsilivaria}{LGR}{\textomicron}{239}
    \DeclareTextComposite{\accdasia}{LGR}{\textrho}{251}
    \DeclareTextComposite{\accpsili}{LGR}{\textrho}{252}

#### Capital letters with diacritics

> In Greek, diacritics are omitted in all-uppercase words, but kept as part of an uppercase initial (written before rather than above the letter).

> The diaytika should also always be used in all-uppercase words (even in cases where they are not needed when writing in lowercase)

> —http://en.wikipedia.org/wiki/Capitalization

In Title Case, place diacritics before instead of above the base character:

    \DeclareTextCompositeCommand{\accdasia}{LGR}{A}{<A}
    \DeclareTextCompositeCommand{\accdasiavaria}{LGR}{A}{<`A}
    \DeclareTextCompositeCommand{\accdasiaoxia}{LGR}{A}{<'A}
    \DeclareTextCompositeCommand{\accdasiaperispomeni}{LGR}{A}{<\char126A}
    \DeclareTextCompositeCommand{\accpsili}{LGR}{A}{>A}
    \DeclareTextCompositeCommand{\accpsilivaria}{LGR}{A}{>`A}
    \DeclareTextCompositeCommand{\accpsilioxia}{LGR}{A}{>'A}
    \DeclareTextCompositeCommand{\accpsiliperispomeni}{LGR}{A}{>\char126A}
    \DeclareTextCompositeCommand{\acctonos}{LGR}{A}{'A}
    \DeclareTextCompositeCommand{\accvaria}{LGR}{A}{`A}

    \DeclareTextCompositeCommand{\accdasia}{LGR}{E}{<E}
    \DeclareTextCompositeCommand{\accdasiaoxia}{LGR}{E}{<'E}
    \DeclareTextCompositeCommand{\accdasiavaria}{LGR}{E}{<`E}
    \DeclareTextCompositeCommand{\accpsili}{LGR}{E}{>E}
    \DeclareTextCompositeCommand{\accpsilioxia}{LGR}{E}{>'E}
    \DeclareTextCompositeCommand{\accpsilivaria}{LGR}{E}{>`E}
    \DeclareTextCompositeCommand{\acctonos}{LGR}{E}{'E}
    \DeclareTextCompositeCommand{\accvaria}{LGR}{E}{`E}

    \DeclareTextCompositeCommand{\accdasia}{LGR}{H}{<H}
    \DeclareTextCompositeCommand{\accdasiavaria}{LGR}{H}{<`H}
    \DeclareTextCompositeCommand{\accdasiaoxia}{LGR}{H}{<'H}
    \DeclareTextCompositeCommand{\accdasiaperispomeni}{LGR}{H}{<\char126H}
    \DeclareTextCompositeCommand{\accpsili}{LGR}{H}{>H}
    \DeclareTextCompositeCommand{\accpsilivaria}{LGR}{H}{>`H}
    \DeclareTextCompositeCommand{\accpsilioxia}{LGR}{H}{>'H}
    \DeclareTextCompositeCommand{\accpsiliperispomeni}{LGR}{H}{>\char126H}
    \DeclareTextCompositeCommand{\acctonos}{LGR}{H}{'H}
    \DeclareTextCompositeCommand{\accvaria}{LGR}{H}{`H}

    \DeclareTextCompositeCommand{\accdasia}{LGR}{I}{<I}
    \DeclareTextCompositeCommand{\accdasiavaria}{LGR}{I}{<`I}
    \DeclareTextCompositeCommand{\accdasiaoxia}{LGR}{I}{<'I}
    \DeclareTextCompositeCommand{\accdasiaperispomeni}{LGR}{I}{<\char126I}
    \DeclareTextCompositeCommand{\accpsili}{LGR}{I}{>I}
    \DeclareTextCompositeCommand{\accpsilivaria}{LGR}{I}{>`I}
    \DeclareTextCompositeCommand{\accpsilioxia}{LGR}{I}{>'I}
    \DeclareTextCompositeCommand{\accpsiliperispomeni}{LGR}{I}{>\char126I}
    \DeclareTextCompositeCommand{\acctonos}{LGR}{I}{'I}
    \DeclareTextCompositeCommand{\accvaria}{LGR}{I}{`I}

    \DeclareTextCompositeCommand{\accdasia}{LGR}{O}{<O}
    \DeclareTextCompositeCommand{\accdasiavaria}{LGR}{O}{<`O}
    \DeclareTextCompositeCommand{\accdasiaoxia}{LGR}{O}{<'O}
    \DeclareTextCompositeCommand{\accpsili}{LGR}{O}{>O}
    \DeclareTextCompositeCommand{\accpsilivaria}{LGR}{O}{>`O}
    \DeclareTextCompositeCommand{\accpsilioxia}{LGR}{O}{>'O}
    \DeclareTextCompositeCommand{\acctonos}{LGR}{O}{'O}
    \DeclareTextCompositeCommand{\accvaria}{LGR}{O}{`O}

    \DeclareTextCompositeCommand{\accdasia}{LGR}{R}{<R}

    \DeclareTextCompositeCommand{\accdasia}{LGR}{U}{<U}
    \DeclareTextCompositeCommand{\accdasiavaria}{LGR}{U}{<`U}
    \DeclareTextCompositeCommand{\accdasiaoxia}{LGR}{U}{<'U}
    \DeclareTextCompositeCommand{\accdasiaperispomeni}{LGR}{U}{<\char126U}
    \DeclareTextCompositeCommand{\acctonos}{LGR}{U}{'U}
    \DeclareTextCompositeCommand{\accvaria}{LGR}{U}{`U}

    \DeclareTextCompositeCommand{\accdasia}{LGR}{W}{<W}
    \DeclareTextCompositeCommand{\accdasiavaria}{LGR}{W}{<`W}
    \DeclareTextCompositeCommand{\accdasiaoxia}{LGR}{W}{<'W}
    \DeclareTextCompositeCommand{\accdasiaperispomeni}{LGR}{W}{<\char126W}
    \DeclareTextCompositeCommand{\accpsili}{LGR}{W}{>W}
    \DeclareTextCompositeCommand{\accpsilivaria}{LGR}{W}{>`W}
    \DeclareTextCompositeCommand{\accpsilioxia}{LGR}{W}{>'W}
    \DeclareTextCompositeCommand{\accpsiliperispomeni}{LGR}{W}{>\char126W}
    \DeclareTextCompositeCommand{\acctonos}{LGR}{W}{'W}
    \DeclareTextCompositeCommand{\accvaria}{LGR}{W}{`W}

Except for the dialytika:

    \DeclareTextComposite{\accdialytika}{LGR}{I}{219}
    \DeclareTextComposite{\accdialytika}{LGR}{U}{223}

Do the same for the LICR macros:

    \DeclareTextCompositeCommand{\accdasia}{LGR}{\textAlpha}{<A}
    \DeclareTextCompositeCommand{\accdasiavaria}{LGR}{\textAlpha}{<`A}
    \DeclareTextCompositeCommand{\accdasiaoxia}{LGR}{\textAlpha}{<'A}
    \DeclareTextCompositeCommand{\accdasiaperispomeni}{LGR}{\textAlpha}{<\char126A}
    \DeclareTextCompositeCommand{\accpsili}{LGR}{\textAlpha}{>A}
    \DeclareTextCompositeCommand{\accpsilivaria}{LGR}{\textAlpha}{>`A}
    \DeclareTextCompositeCommand{\accpsilioxia}{LGR}{\textAlpha}{>'A}
    \DeclareTextCompositeCommand{\accpsiliperispomeni}{LGR}{\textAlpha}{>\char126A}
    \DeclareTextCompositeCommand{\acctonos}{LGR}{\textAlpha}{'A}
    \DeclareTextCompositeCommand{\accvaria}{LGR}{\textAlpha}{`A}

    \DeclareTextCompositeCommand{\accdasia}{LGR}{\textEpsilon}{<E}
    \DeclareTextCompositeCommand{\accdasiaoxia}{LGR}{\textEpsilon}{<'E}
    \DeclareTextCompositeCommand{\accdasiavaria}{LGR}{\textEpsilon}{<`E}
    \DeclareTextCompositeCommand{\accpsili}{LGR}{\textEpsilon}{>E}
    \DeclareTextCompositeCommand{\accpsilioxia}{LGR}{\textEpsilon}{>'E}
    \DeclareTextCompositeCommand{\accpsilivaria}{LGR}{\textEpsilon}{>`E}
    \DeclareTextCompositeCommand{\acctonos}{LGR}{\textEpsilon}{'E}
    \DeclareTextCompositeCommand{\accvaria}{LGR}{\textEpsilon}{`E}

    \DeclareTextCompositeCommand{\accdasia}{LGR}{\textEta}{<H}
    \DeclareTextCompositeCommand{\accdasiavaria}{LGR}{\textEta}{<`H}
    \DeclareTextCompositeCommand{\accdasiaoxia}{LGR}{\textEta}{<'H}
    \DeclareTextCompositeCommand{\accdasiaperispomeni}{LGR}{\textEta}{<\char126H}
    \DeclareTextCompositeCommand{\accpsili}{LGR}{\textEta}{>H}
    \DeclareTextCompositeCommand{\accpsilivaria}{LGR}{\textEta}{>`H}
    \DeclareTextCompositeCommand{\accpsilioxia}{LGR}{\textEta}{>'H}
    \DeclareTextCompositeCommand{\accpsiliperispomeni}{LGR}{\textEta}{>\char126H}
    \DeclareTextCompositeCommand{\acctonos}{LGR}{\textEta}{'H}
    \DeclareTextCompositeCommand{\accvaria}{LGR}{\textEta}{`H}

    \DeclareTextCompositeCommand{\accdasia}{LGR}{\textIota}{<I}
    \DeclareTextCompositeCommand{\accdasiavaria}{LGR}{\textIota}{<`I}
    \DeclareTextCompositeCommand{\accdasiaoxia}{LGR}{\textIota}{<'I}
    \DeclareTextCompositeCommand{\accdasiaperispomeni}{LGR}{\textIota}{<\char126I}
    \DeclareTextCompositeCommand{\accpsili}{LGR}{\textIota}{>I}
    \DeclareTextCompositeCommand{\accpsilivaria}{LGR}{\textIota}{>`I}
    \DeclareTextCompositeCommand{\accpsilioxia}{LGR}{\textIota}{>'I}
    \DeclareTextCompositeCommand{\accpsiliperispomeni}{LGR}{\textIota}{>\char126I}
    \DeclareTextCompositeCommand{\acctonos}{LGR}{\textIota}{'I}
    \DeclareTextCompositeCommand{\accvaria}{LGR}{\textIota}{`I}

    \DeclareTextCompositeCommand{\accdasia}{LGR}{\textOmicron}{<O}
    \DeclareTextCompositeCommand{\accdasiavaria}{LGR}{\textOmicron}{<`O}
    \DeclareTextCompositeCommand{\accdasiaoxia}{LGR}{\textOmicron}{<'O}
    \DeclareTextCompositeCommand{\accpsili}{LGR}{\textOmicron}{>O}
    \DeclareTextCompositeCommand{\accpsilivaria}{LGR}{\textOmicron}{>`O}
    \DeclareTextCompositeCommand{\accpsilioxia}{LGR}{\textOmicron}{>'O}
    \DeclareTextCompositeCommand{\acctonos}{LGR}{\textOmicron}{'O}
    \DeclareTextCompositeCommand{\accvaria}{LGR}{\textOmicron}{`O}

    \DeclareTextCompositeCommand{\accdasia}{LGR}{\textRho}{<R}

    \DeclareTextCompositeCommand{\accdasia}{LGR}{\textUpsilon}{<U}
    \DeclareTextCompositeCommand{\accdasiavaria}{LGR}{\textUpsilon}{<`U}
    \DeclareTextCompositeCommand{\accdasiaoxia}{LGR}{\textUpsilon}{<'U}
    \DeclareTextCompositeCommand{\accdasiaperispomeni}{LGR}{\textUpsilon}{<\char126U}
    \DeclareTextCompositeCommand{\acctonos}{LGR}{\textUpsilon}{'U}
    \DeclareTextCompositeCommand{\accvaria}{LGR}{\textUpsilon}{`U}

    \DeclareTextCompositeCommand{\accdasia}{LGR}{\textOmega}{<W}
    \DeclareTextCompositeCommand{\accdasiavaria}{LGR}{\textOmega}{<`W}
    \DeclareTextCompositeCommand{\accdasiaoxia}{LGR}{\textOmega}{<'W}
    \DeclareTextCompositeCommand{\accdasiaperispomeni}{LGR}{\textOmega}{<\char126W}
    \DeclareTextCompositeCommand{\accpsili}{LGR}{\textOmega}{>W}
    \DeclareTextCompositeCommand{\accpsilivaria}{LGR}{\textOmega}{>`W}
    \DeclareTextCompositeCommand{\accpsilioxia}{LGR}{\textOmega}{>'W}
    \DeclareTextCompositeCommand{\accpsiliperispomeni}{LGR}{\textOmega}{>\char126W}
    \DeclareTextCompositeCommand{\acctonos}{LGR}{\textOmega}{'W}
    \DeclareTextCompositeCommand{\accvaria}{LGR}{\textOmega}{`W}

Except for the dialytika:

    \DeclareTextComposite{\accdialytika}{LGR}{\textIota}{219}
    \DeclareTextComposite{\accdialytika}{LGR}{\textUpsilon}{223}

## UPPERCASE

The common Greek font encoding definitions in greek-fontenc.def extend the uclclist with Greek LICR macros. Here, we add LGR specific “hiatus” handling.

Composite commands for Latin transliteration:

    \DeclareTextCompositeCommand{\LGR@hiatus}{LGR}{A}{\LGR@A@hiatus}
    \DeclareTextCompositeCommand{\LGR@hiatus}{LGR}{E}{\LGR@E@hiatus}

TODO: What does the LGR@hiatus command “see” if a Unicode literal follows?

    % \DeclareTextCompositeCommand{\LGR@hiatus}{LGR}{\symbol{"ce}}{bluff}
    % \DeclareTextCompositeCommand{\LGR@hiatus}{LGR}{"cf}{blaff}
    % \DeclareTextCompositeCommand{\LGR@hiatus}{LGR}{ι}{blaff}

Look ahead and place a diaeresis on Ι or Υ:

    \DeclareTextCommand{\LGR@A@hiatus}{LGR}{%
      \LGR@ifnextchar{I}{A\"}{%
        \LGR@ifnextchar{U}{A\"}{%
          \LGR@ifnextchar{\textIota}{A\"}{%
            \LGR@ifnextchar{\textUpsilon}{A\"}{A}%
          }%
        }%
      }%
    }
    \DeclareTextCommand{\LGR@E@hiatus}{LGR}{%
      \LGR@ifnextchar{I}{E\"}{%
        \LGR@ifnextchar{U}{E\"}{%
          \LGR@ifnextchar{\textIota}{E\"}{%
            \LGR@ifnextchar{\textUpsilon}{E\"}{E}%
          }%
        }%
      }%
    }

Unfortunately, the lookahead breaks kerning.

Alternatives tried:

- CompositeCommands fail at the end of a macro, e.g. \emph{\'a}

      \DeclareTextCommand{\LGR@A@hiatus}{LGR}{A}
      \DeclareTextCommand{\LGR@E@hiatus}{LGR}{E}

      \DeclareTextCompositeCommand{\LGR@A@hiatus}{LGR}{}{A}
      \DeclareTextCompositeCommand{\LGR@A@hiatus}{LGR}{I}{A\"I}
      \DeclareTextCompositeCommand{\LGR@A@hiatus}{LGR}{U}{A\"U}

- The glyph No 12 is a special “Upcase Alpha” that in ligature with Y and I adds a diaresis to them. However, it seems that it has only kerning definitions for I and Y (as it is not intended for direct use)

      \DeclareTextComposite{\LGR@hiatus}{LGR}{A}{12}

  No such glyph exists for E but this is no problem as E does not require kerning anyway.