What is the difference between the three similar methods - check_*_for_os

[saveshodhan]

In the driver specific files (/exscript/Exscript/protocols/drivers) we see three similar methods:
check_head_for_os
check_protocol_for_os
check_response_for_os

Each of these accept a string and upon a successful match, a confidence value is set.

Some drivers have just one of these methods, some have multiple.
Is there a convention as to which method is to be used where?

Looking at the files, it seems that:

• the check_response_for_os is used to match content from the banner
• the check_head_for_os is used to match content from the text that appears before username is prompted
• not sure about check_protocol_for_os it only appears in ios.py