The parsing string is in two parts, separated by an underscore.

Part 1: part of speech:

A = Adjective
N = Noun
V = Verb
R = Pronoun (2 columns)
   RA = Articl
   RD = Demonstrative
   RI = Interrogative/Indefinite
   RP = Personal/Possessive
   RR = Relative
   RX = hostis
C = Conjunction
X = Particle
I = Interjection
M = Indeclinable Number
P = Preposition
D = Adverb

Part 2: Parse Code
 Nouns and Pronouns (3 columns)
   col.1=case: N(om) G(en) D(at) A(ccus) V(ocative)
   col.2=number: S(ing) D(ual) P(l)
   col.3=gender: M(asc) F(em) N(eut)

 Adjectives (up to 4 columns)
   cols.1-3 as with Nouns (above)
   col.4=degree if irregular: C(ompar) S(uperl)
 Verbs (to 5 cols, except participle)        
   col.1=tense: P(resent) I(mperfect) F(ut) A(or) X(Perfect) Y(Pluperfect)
   col.2=voice: A(ctive) M(iddle) P(assive)           
   col.3=mood: I(ndicative) D(Imperative) S(ubjunct)  O(pt) N(Infin) P(Ptcp)   
   col.4=person: 1 2 3
   col.5=number as Noun col.2 
   cols.4-6 Particple as for Noun