how to understand TCL list

HTTP::header values xyz

 

it will return a TCL list if there are more than one xyz in header

 

so my question is :

 

class match [HTTP::header values xyz] contains data_group

 

does it work?

 

if it is a list ,such as

 

111

 

222

 

how can it be compared with one entry in data_group?

 

thx in advance