"pascal" keyword in C++

[humble_learner]

As part of a project to port 16 bit Borland C++ code to VC++, I came across the following statement in the BC++ code. Can someone please let me know what the keyword "pascal" means over here ?

friend BitVec pascal operator ^ (……

Is it safe to retain code by removing " pascal " in the VC++ version or is there a corresponding substitute ?
What is "pascal" used for ?

[humptydumpty]

just read some good tutorial for calling convention.you are gointg to find everything.have a look for this also __stdcall