@ac md ps

What does inria mean by "ac." "md." "ps." in the following three?

**pacati पचति pr प्र्. (1 १) ac अच्. sg स्ग्. 3 ३ (pac पच्)

**pacate पचते pr प्र्. (1 १) ac अच्. sg स्ग्. 3 ३ (pac पच्)

**pacyate पच्यते ( pr. ps. sg. 3 ) (pac पच्)

Here,

ac tells us that the ending is flat and doershowing — /tip
md that it is bent and doershowing — /ta
ps that it is bent and not doershowing — /ta

Why does (1) appear in the forst two but not in the third?

The (1) tells you that the first two get /zap before /tip or /ta.

But you don't need to know the verb class to form **pacyate पच्यते, because all classes get /yak.