Please see below a paragraph which is actually from OCC documentation(iges.pdf)
"All definitions in IGES version 5.3 are recognized but only 3D
geometric entities are translated. When the processor encounters data, which is not translated, it ignores it and writes a message identifying the types of data, which was not handled. This message can be written either to a log file or to screen output"
Based on the above para, I have couple of doubts.
1. Which are those entities not coming under 3D geometric entities ?
2. How can write error messages to a log file?
Which class or fucntion is used for it?