About File/Directory Masks...

A file name mask is used to selectively qualify directory entries.а A wildcard is a special character that can fill in for missing letter(s) in file and directory names when used to add specificity to OS commands.а Although there are various ways to define the syntax and semantics of a mask string, we will use the following rules:

A mask has two parts, one for the file name and the other for the extension.а If an extension mask is included, it is separated from the file mask by a period.
A null file mask string qualifies all entries (regardless of extension.)
An С*Т qualifies all characters to the right and cannot be followed by any characters (other than a period and an extension mask.)а There can be only one У*Ф per file name and/or extension mask.а Thus a single У*Ф would select all files without an extension.а A У*.*Ф mask would be the same as a null string and select all files with or without an extension.
A С?Т is a wild card for any single character and requires the presence of a character in the file name to qualify.а It may be used multiple times in the file name and/or file extension mask.

Examples:аааааа *.*аааааааааааааааааааааааааа All files

ааааааааааааааааааааааа B*ааааааааааааааааааааааааа All files beginning with СBТ and no extension

ааааааааааааааааааааааа ???*.Cаааааааааааааааааа All files of length at least 3 with СCТ extension

ааааааааааааааааааааааа *.TXTааааааааааааааааааааа All files with УTXTФ extension