If a unit number is uncertain, use the unit abbreviation followed by the number and a question mark enclosed in parentheses, after the unit count.

300 ## $a 1 film reel of 3 (r2?) (ca. 7 min., 600 ft.) : $b si., b&w ; $c 35 mm. $3 master pos pic.

300 ## $a 2 film reels of 5 (r3?, 5) (ca. 17 min., 1,520 ft.) : $b sd., b&w ; $c 35 mm. $3 viewing print.

300 ## $a 1 videocassette of 4 (U-Matic) (c3?) (40 min.) : $b sd., col. ; $c 3/4 in. $3 viewing copy.

If the unit number is unknown, use the unit abbreviation followed by a question mark in the parentheses.

300 ## $a 1 film reel of 8 (r?) (ca. 7 min., 650 ft.) : $b si., b&w ; $c 35 mm. $3 dupe neg pic.

300 ## $a 6 film reels of 10 (rl-5, r?) (ca. 44 min., 3,900 ft.) : $b sd., b&w ; $c 35 mm. $3 answer print.

See also:

5B4.  Incomplete works

5B.  Extent of work and specific material designation

5.  Physical Description Area