You will see
MCD_ identifiers for strings and constant strings in the CMarkup method declarations.
MCD_STR is defined in Markup.h as a string class which, depending on your project, can be one of the following:
MCD_CSTR is a constant string argument to a CMarkup method. It is implemented in CMarkup as a
struct which allows either a constant reference to a string object (
const MCD_STR&) or a zero terminated string.
MCD_PCSZ is a pointer to a constant zero terminated string.
These were introduced with CMarkup release 9.0 in which
CMarkup can be compiled for either MFC or STL strings. The
MCD_ prefix stands for Markup Compiler Dependency, and is used for all of the defines for the text and string platform differences documented in Unified CMarkup for STL and MFC.