c++ - What is xmath.h for? -

while trying older code (probably around 2001-2005 or so) build, cam across following conditional include:

#if _msc_ver >= 1300 #include <xmath.h> #endif

i building visual studio 2012:

microsoft (r) c/c++ optimizing compiler version 17.00.61030 x86

which gives fatal error on include:

fatal error c1083: cannot open include file: 'xmath.h': no such file or directory

so me, looks non-standard microsoft specific header supported _msc_ver 1300 (msvc++ 7.0) on, no longer supported. questions are:

is assumption correct? if 'yes', version of msvc++ header no longer supported?
what purpose of including xmath.h header? code compiles fine without it, can leave out?
is xmath.h documented somewhere? cannot seem find decent documentation on using simple google search.

xmath.h part of internal implementation of microsoft's standard c++ library. there no reason code use it. if code compiles fine without it, dump it.

SoEM