# Annotation Glossary

### A

allow-none

  NULL is OK, both for passing and for returning.

array

  Parameter points to an array of items.

### C

closure

  This parameter is a 'user_data', for callbacks; many bindings can pass NULL here.

### D

default

  Default parameter value (for in case the shadows-to function has less parameters).

### E

element-type

  Generics and defining elements of containers and arrays.

### I

in

  Parameter for input. Default is transfer none.

inout

  Parameter for input and for returning results. Default is transfer full.

### N

nullable

  NULL may be passed as the value in, out, in-out; or as a return value.

### O

optional

  NULL may be passed instead of a pointer to a location.

out

  Parameter for returning results. Default is transfer full.

out caller-allocates

  Out parameter, where caller must allocate storage.

### S

scope async

  The callback is valid until first called.

### T

transfer container

  Free data container after the code is done.

transfer full

  Free data after the code is done.

transfer none

  Don't free data after the code is done.

type

  Override the parsed C type with given type.