Which tool is the map file used with?
thx chris for your answer
the map file is used in the cadence first encounter to stream out the .gds2 file
and i use the same map file in opening the gds file in calibre DESIGNrev
I see what you mean now.
DATATYPE is similar to LAYER in a gds file.
Polygon data is on some layer, and in a gds file there is also the concept of datatype. Some people use both of these as a way to keep different kinds of data separated. Some people don't use datatype at all, or they ignore it, and then the default is usually zero.
Calibre is more "layer" focused. In Calibre DRC and LVS it's all about the layer number and the layer name. If the gds/stream input data happens to be purposely organized by datatype and layer at the same time, then the LAYER MAP statement in Calibre is used to show which initial layer/datatype "pairs or combinations" will be mapped to a certain final layer number in Calibre.
DESIGNrev can be datatype aware. If your gds file has polygons on layer 14 with datatype 2 then you might see this in the layer palette as "14.2".
There is more discussion of this kind of layermap file in the DESIGNrev user's manual. Here's a link if it helps: