Template type Note also that there are two types of templates. The types are specified with the first character of templates. Unigram template: first character, 'U' This is a template to describe unigram features. When you give a template "U01:%x[0,1]", CRF++ automatically generates a set of feature functions (func1 ... funcN) like: func1 = if (output = B-NP and feature="U01:DT") return 1 else ret