This hasn't been correct since 9.3 added "latex-longtable".
I left the phraseology "Unique abbreviations are allowed" alone.
It's correct as far as it goes, and we are studiously refraining
from specifying exactly what happens if you give a non-unique
abbreviation. (The answer in the back branches is "you get a
backwards-compatible choice", and the answer in HEAD will shortly
be "you get an error", but there seems no need to mention such
details here.)
Daniel Vérité
Discussion: https://postgr.es/m/
cb7e1caf-3ea6-450d-af28-
f524903a030c@manitou-mail.org
<literal>latex</literal> (uses <literal>tabular</literal>),
<literal>latex-longtable</literal>, <literal>troff-ms</literal>,
<literal>unaligned</literal>, or <literal>wrapped</literal>.
- Unique abbreviations are allowed. (That would mean one letter
- is enough.)
+ Unique abbreviations are allowed.
</para>
<para><literal>unaligned</literal> format writes all columns of a row on one