cvs auto versioning

[Detlef Brendle]

hi all,
does anybody know how to versioning (tag) a set of cvs files automatically
with an ant script?
e.g a vendor tag R2.7 exists from a previous versioning. now when I run my
ant script I would like to tag the verison with R2.8 or R2.71.

how could I do this,
+
thanks,
detlef