What is "a clerical error"

Clerical \Cler"ic*al\, a. [LL. clericalis. See Clerk.]

1. Of or pertaining to the clergy; suitable for the clergy. ``A clerical education.''
   --Burke.

2. Of or relating to a clerk or copyist, or to writing. ``Clerical work.''
   --E. Everett.

3. characteristic of the work performed by a clerk, secretary, or copyist, or suitable to be performed by a clerk. ``Clerical staff.''

   A clerical error, an error made in copying or writing.