If you do not supply a path, MrDebug searches the current directory for the file. If the file cannot be found in the current directory, MrDebug will search the directories found within the 'Path for source' option under the options menu. If it still cannot find the source code file it will then search the SOURCE environment variable. AND if it still can't find the file it will take a look at the INCLUDE environment variable.
Ideal for late breaking READ.ME files. You can view any ASCII text file within the normal source code window.