Is there a concise term or abbreviation for "Decimal Places"?
Solution 1:
DP is the official abbreviation for "decimal places".
http://www.abbreviations.com/abbreviation/Decimal+Places
If there is concern about ambiguity, it is always appropriate to provide a key describing the labels for clarity.
Noun
An explanatory list of symbols used in a map, table, etc.
Solution 2:
I appreciate the input from everyone. While I like the idea of an abbreviation, I've never seen DP used for decimal places (although you have my up vote for the concept and source). I've explained in the question that precision is out and I'm not convinced that decimals conveys the same meaning as decimal places, so I'm considering the following:
Value Decimal
Places
_____________________________________
10.12 2
1.123 3
I'll anticipate some down votes as this is not an EL&U usage answer so much as a simple change to formatting.