Most abbreviations are nouns and can be used with more than one gender. Of course, abbreviations have no endings but the surrounding context can reveal their underlying gender whenever gender agreement is required by the Czech grammar. Neuter is always possible. Besides that, the author may use the gender of the main word of the abbreviated expression. The matter can become further complicated with foreign expressions if their Czech gender does not correspond to the gender in the original language.

In order to keep the rule of a noun lemma not having more than one gender, tags of abbreviations should use the X gender code. This is often broken in PDT 2.0 and abbreviations are the most frequent nouns to have two different genders.

There is a similar problem with abbreviations of personal names (J_:B_;Y can mean both Jan and Jana). The difference is that here the neuter interpretation is not plausible. Nevertheless, the tagset does not provide any code for {M+F} genders, so the best bet is to stick with X.