@Joe Riel 

Joe, certainly, I know this straightforward way for debugging. But I ask about possible sophisticated way for doing tracing directly in statements sequence.

Thank you for your reply, but before posting my question I tried different encoding for an input format. Unfortunately, on my platform (Win 7 x86 Rus, Maple 17.01) UTF-8 yields unsatisfied result, whether the input file has BOM or not:

ReadLine reads all lines, but characters are completely distorted.

Is your result of reading valid?

Thank you for your reply, but before posting my question I tried different encoding for an input format. Unfortunately, on my platform (Win 7 x86 Rus, Maple 17.01) UTF-8 yields unsatisfied result, whether the input file has BOM or not:

ReadLine reads all lines, but characters are completely distorted.

Is your result of reading valid?

Yes, r. 17.01 has a bulk of impressive improvements, but the legacy crash of Classic interface during worksheet saving continues to disturb users.....

I can add, that first time faced with bugs and crushed in 16 release. All previous versions worked properly. To my mind, MapleSoft stopped to pay attention to this Interface and this is main cause of such a sad thing.