Here is a list of abbreviations I typically use when grading papers. I will update it as necessary.

adv. — Use an adverb here, not an adjective.

A.L. — Your essay is significantly longer than the assigned length.

a.v. — Your sentence would be more lively and effective if you used an action verb instead of have or be.

awk. — Awkward syntax or choice of words.

C.II., etc. — See the specific number mentioned of Schlabach's Ten Commandments of Good Historical Writing

col. — This language is colloquial. That is, you are writing how we speak or how we write in everyday life. Formal English prose requires different language. Examples: contractions and you/I.

c.o.w. — Your choice of words is ambiguous or does not accurately convey your meaning.

c.u. — Comma usage.

D. — You need to use a dictionary both for the meaning of your words and their usage.

d.s. — Double subject. Your sentence has a two subjects, but it should only have one. Incorrect example: "My friend, she is from Spain." Correct examples: "My friend is from Spain." "She is from Spain."

E.I. — Essay ingredients. See "What Ingredients Must an Essay Contain?" This blog post talks both about the kinds of paragraphs you need as well as what goes into each paragraph.

f.s. — Your font size is either too big or too small. Use a standard 12 point font.

i — Use italics here.

L.S. — Your line spacing is incorrect. Your essay should be double spaced.

M. — Your margins are too big or too small. They should be 1" or 1.25".

m.o. — Missing object. Your phrase requires a direct or indirect object, but you did not use one.

m.s. — Missing subject. Every sentence requires a subject, but yours has none.

n.i. — No italics necessary.

o.w. — This is written as one word. A dictionary can help you to avoid such mistakes.

p.c. — Parallel construction. After reading the information on the page to which the term is linked, try this parallel structures quiz.

pl. — Plural. I usually use this abbreviation in conjunction with its counterpart, sg., for singular, to point out that you are mixing up plural and singular nouns or singular and plural noun and verb combinations. There might also be a problem with a singular or plural pronoun.

pp. — Pages.

p.t. — Write consistently in the past tense. (See Schlabach's ninth commandment.)

p.v. — Avoid the passive voice.

rel? — Relevance? You might make an interesting point, but is it relevant to the specific argument at hand?

rep. — Repetition. Either you are repeating a theme covered earlier, or you have repeated a word unnecessarily within the same sentence or two. Sometimes I include a question mark, because I see repetition, but maybe you were actually trying to make a new point. If so, I am unclear about how new the information in question actually is.

r.o. — Run-on sentence. Your "sentence" contains two independent clauses, which you need to separate with a period or semi-colon.

R.T.D. — Read the directions.

s.f. — Sentence fragment. In other words, the "sentence" in question is not a complete sentence with subject and predicate.

sg. — Singular. (See pl. above.)

sig? — Significance? In other words, why does the fact you mention matter? Why are the circumstances you describe significant?

sp. — Incorrect spelling.

T? — Your essay is missing a title, but it needs one. Make it descriptive without trying to force it to be cute.

trans? — Your paragraph is lacking a transition sentence that moves the reader from the previous paragraph (and topic) into this one.

t.w. — This is written as two words.

W.C. — Make an appointment to visit the Writing Center. (George Mason University Writing Center)

w.o.n. — Write out numbers smaller than 100. Instead of 20, write twenty. Instead of 10th, write tenth.

¶ — Paragraph break.

# — Missing page number.

[ ] — The square brackets indicate unnecessary words.

. . . — This ellipsis invites you to expand on the point.

_ _ _ _ — I use a dashed underline to "undo" a correction I previously made.

// — [I changed this one to p.c. See above.]

? — I do not understand what you are trying to say here.

?? — Are your sure? This statement does not make sense to me. (But I would be happy if you showed me I am wrong.)

??? —- This sentence contradicts the facts as I understand them.

?! — Same as "???"

! — Important point.

√ — Just a note to myself to recall part of your argument.