what is 1056 in this rom? cm-12.1-20151023-1056-UNOFFICIAL-p3100.zip.

i own p3100, i want to install cm12.1. but which build is good? should i download by watching its date of build i.e cm-12.1-20151023-1056 or should i download by watching this number ( 1056-UNOFFICIAL). which is best bug free in these?