The mIRC scripting language, often unofficially abbreviated to "mSL", is the scripting language embedded in mIRC, an IRC client for Windows.
Scripts are stored as either plain text files, usually with a .mrc file extension, or as INI files. They however can be stored with any extension. It can be: .exe, .script, etc. Multiple script files can be loaded at one time, although in some cases, one script will conflict with another and cause one or both of them to no longer work properly.
mIRC scripting involves a peculiar nomenclature that is not entirely consistent with most of the rest of the programming world. (Most notably, the term identifier—which in most languages refers to the name of a variable or function (whether it returns a value or not)—in mIRC refers specifically to a value returning function.)
The above is intended for singular access to the file. Because each time you issue $read or /write you open and close the file for access. Multiple accesses, during a loop for instance, is best handled through /fopen, /fwrite and /fclose. Since this opens the file only once. In some cases /filter and /savebuf is an even more efficient (non scripted loop) method.