Enumerations for _Constraint_file.Constraint_subtype (An open enumeration)
`alignment tensor` | enumeration_text
`chirality` | enumeration_text
`disulfide bond` | enumeration_text
`general distance` | enumeration_text
`hydrogen bond` | enumeration_text
`NOE` | enumeration_text
`NOE buildup` | enumeration_text
`NOE not seen` | enumeration_text
`Not applicable` | enumeration_text
`peptide` | enumeration_text
`prochirality` | enumeration_text
`ring` | enumeration_text
`ROE` | enumeration_text
`symmetry` | enumeration_text