[Zope] Re: dtml-Variablen in <dtml-in> loops?

Hello,

[...] <dtml-in "DATA[start:end]"> or whatever. [...]

yes, such a syntax should _theoretically_ do the proper thing, but I always get a "Error Value: sequence index must be integer" when trying to do the [start:end] stuff within the <dtml-in> Tag. Any Ideas how I could either a) use "DATA[start: x + y]" in Zope (where x and y are dtml-Variables!) b) do <dtml-in DATA start=1 end= x + y (where x and y are dtml-Variables!) Thanks again, Philipp