Assura to Calbire conversion questions..

I have some questions regarding Assura to Calibre conversion, please
help hinting or answering questions you can.. thanks in advance.

- How to convert sentences like this to Calibre:
if (avSwitch("switch") then
actions...
errorLayers(....)
)
(will I use Preprocessors like $IFDEF ...??)

- How to convert to Calibre:
keepLayer(layer1 [layer2...])

- Where should I print (as using printf() in Assura) in Calibre? Log
file? Or output file?? Or use "SVRF ERROR()"?

- No DF2 supported in Calibre, then should I just neglect its layers
definition?? Or there's a method of conversion?

- What does defining layers more than once mean(assigning to the same
layer name more than one value!)??
e.g. L1 = geomAndNot( A B)
... after few lines of other layers zwn (n: 2 -> 8) definitions, and
using them in another layer
L1 = geomAndNot( C B) // same name and different value!!

Thanks a lot and kind regards,
Ahmad,