Tim Russell writes:

.... 2 dimensional list access and modification of elements .... I can easily access the value of an element using:

<dtml-var "col[index1][index2]">

However, the difficulty comes when trying to change the value of one of these elements....

There is no easy and safe way to do it in DTML (because a list does not have a method to replace a list element. If interested in a hack, you may look at the list methods "remove" and "insert"). The easiest thing is to write an external (or Python) method. Dieter