West02, Jones on End-to-End Accuracy Standards, Slide 2

Legal terms applying to paper-based systems:

Prescribed mark
The form of mark (or hole) the voter is instructed to make in order to cast a vote.
Example: An X in the box by the candidate's name.

Acceptable mark
Any mark that meets the legal criteria to be counted as a vote.
Example: Two lines the intersection of which is in the box or a checkmark, the vertex of which is in the box.

Why distinguish between prescribed and acceptable marks?
If the voter's intention can be ascertained with reasonable certainty, ordinarily the ballot should be given effect and counted in accordance with that intention, provided the voter has substantially complied with statutory requirements and no essential mandate of the law is thereby violated.

Corpus Juris Secundum Volume 29, Elections, Page 496.