How to get Topology ID (for PCI)

[mvas82]

How is it possible to get topology id information of a solid surface when clicking on it?
Want to get that information on runtime for my PCI.

Example:
%INITDIGINFO=gdh
%ASKDIGINFO=nret,Numdig=choose face=[gdh],[#ENTITYDIG],162
%calc=counter=0
%QUERYDIGINFO=nret=[gdh],[counter]

%if [counter]=0
Get topology information here
%gosub=blablabla
%endif

**subprgm**
%InitDigInfo=gdh1
%AddEntnoDig=[gdh1],[&entno],[#DIG_2DSNAP],[#DIR_FORWARD],[topology1-variable]
%AddFinishDig=[gdh1],[#FINISH]
**subprgm**

Thanks