Do not assume that file names must be 8.3 compatible. Be reasonable though. Let the file names be as long as necessary, but no longer. Some operating systems limit file names to 32 characters.
Allowing spaces would cause problems with certain versions of existing industry tools and does not provide additional clarity.
Most source control systems will not be able to handle file names that start with numbers.
All file names within an EDK II source tree must comply with the following regular expression:
That is, a letter followed by zero, or more, letters, underscores, dashes, or digits followed by a period followed by one or more letters or digits.