Why use underscores in names?

Question

Hi,
Ive noticed that some classes and variables etc use an underscore _ at the start of the word.
E.g.
org.omg.CORBA._PolicyStub
with the method,
String[] _ids()
Why is this?
I can understand possibly using underscores between two words although I dont use that myself. But why at the start of the word?
Cheers, Jim

Answer 1

In the "good old times" of C this convention was considered as reserved for the internal functions (methods are called functions in C) of the standard library.
Since all C functions were global - and one could / had to use also global variables, this distinction made sense.
Though it's ugly - at least according to my taste. But a "normal" C programmer did almost never see one of these identifiers.
If you use it in Java to mark the scope of a variable, I consider it senseful as well (and ugly again).
I myself prefer i for instance, s for static and l for local - the "name" of the variable starts with upper case then, like:String lMessage = iMessage + " ...";
if( lMessage.length() < 10 )
  iMessage = lMessage;(dummy example)