  We delineate a procedure to classify 6d N=(1,0) gauge theories composed, in
part, of a semi-simple gauge group and hypermultiplets. We classify these
theories by requiring that they satisfy some consistency conditions. The
primary consistency condition is that the gauge anomaly can be cancelled by
adding tensor multiplets which couple to the gauge fields by acting as sources
of instanton strings. Based on the number of tensor multiplets required to
cancel the anomaly, we conjecture that the UV completion of these consistent
gauge theories (if it exists) should be either a 6d N=(1,0) SCFT or a 6d
N=(1,0) little string theory.
