A DOS 8.3 file name is composed of two parts: a name, which can be up to eight characters long, and an optional extension, which can be up to three characters long. The name and extension are separated by a period. A file name may not begin with a period. Extensions are typically not added to directory names because it makes discerning them from filenames difficult. The extension is DOS' way of determining which of the four basic functions a file performs: executable (.exe or .com), support (.ini, .cgf, or .dll), data (.doc, .txt, .xls, .dbf, and .dxf), and batch (.bat).
In general, DOS filenames use only letters and numerals. Upper and lower case letters are considered identical. In addition, the following symbols can be used in file names:
` ~ ! @ # $ % ^ & ( ) _ - { } '
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Valid DOS file names |
Invalid DOS file names |
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RESULTS.TXT SEARCH.#1 READ.ME! MY.DOC A.A A {MYFILE} |
MYRESULTS.TXT (MYRESULTS is 9 characters) SEARCH.RESULTS (RESULTS is 7 characters) ONE.TWO.3 (Only use one period) /.\ (Invalid punctuation symbols) |