Answer:

ENC

Answer	Crossword Clue
ENC	Abbr. in a letter
ENC	Business abbr.
ENC	Ref. wk.

ENC	SASE, e.g.
ENC	SASE, often
ENC	Ref. work
ENC	Ref. book
ENC	In an env.
ENC	In the env.
ENC	Env. insertion
ENC	Bus. letter abbr.

ENC	Business letter abbr.
ENC	SASE, for example
ENC	Addl. item in an envelope
ENC	SASE, perhaps: Abbr.
ENC	Addl. document in an envelope
ENC	It may support a written claim: Abbr.
ENC	SASE, for one
ENC	It may be a copy of a ck.

ENC	Something besides the ltr.
ENC	Compton's, for one: Abbr.
ENC	Doc. with a ltr.
ENC	Env. in an env., say
ENC	Letter-bottom abbr.
ENC	Cover letter letters
ENC	Cause of an env. bulge
ENC	In this pkg.

ENC	It comes in vols.
ENC	Bottom-of-letter abbr.
ENC	Letter inclusion, briefly
ENC	Large ref. work
ENC	Ltr. extra
ENC	Abbr. on a cover letter
ENC	Abbr. under a signature
ENC	Bus. letter extra

ENC	Env. stuffer
ENC	RSVP, e.g.
ENC	Env. extra
ENC	Research tool (abbr.)
ENC	Wedding RSVP, e.g.