First, this comprehensive list of codes IN SPANISH for correcting Spanish, from the University of Rhode Island. Click in!
I have a list also of correction codes from this source.
AA Adjective/noun agreement wrong (includes gender and number)
AC Accent wrong or missing
AGR Subject/verb agreement problem; make sure subject agrees with verb.
AP Personal ‘a’ required
ART Article wrong or missing (includes definite [el/la…] vs. indefinite [un/uno/una…])
CC Wrong copula choice; choose between ser and estar
GEN Gender wrong; check whether noun is masculine or feminine and make it agree with article.
INF Infinitive needed
OP Object pronoun wrong or missing; may include direct/indirect object pronouns or masculine/feminine; make sure pronoun agrees with the noun it is replacing.
PART Participle form of verb required; be sure the participle agrees with the noun if it is being used as an adjective or in the passive voice. Ex.: Las composiciones fueron revisadas por el profesor. If it is used in a perfect tense, use the masculine singular form. Ex: Yo he estudiado para el examen.
PREP Preposition wrong or missing
REL Relative pronoun wrong; frequently ‘que’ is missing. Ex.: La casa (que) yo compré.
REF Reflexive pronoun wrong or missing
SP Spelling error
SPN Subject pronoun problem; Ex: Yo, tú, él, ella, Ud., nosotros, ellos, ellas, Uds.
TNS Tense incorrect (includes preterit/imperfect distinction)
VF Verb improperly conjugated (includes wrong verb forms, e.g., stem-changing verbs)
WC Word choice – more appropriate word required; vocabulary error; may be the result of a direct translation from English.
WO Word order incorrect