Defines the name of a macro. This name can be used to refer to this macro in the MACROUSE or MOVIE commands. This command indicates that we are starting the definition of a macro. A conditional macro is a macro with if-then blocks and is evaluated in the physics code. Conditional macros must start with an if-then statement and must end with endif. If statements are like fortran ifs except the logical operators are not deliminated with `.'s. Also the operands can only be global variables including the user set variables var0 through var9. (Note: The end of the macro is indicated by MACROEND.)