Bad file name or number
A statement or command refers to a file with a file number or file name that is not specified in the Open statement or is out of the range of file numbers specified earlier in the application.
The filename used may be invalid. When using MS DOS, you will need to use the following conventions for naming files and directories.
The name of a file or directory can have two parts: a name and an optional extension. The two parts are separated by a period (for example, MYFILE.NEW).
The name can contain up to eight characters, and the extension can contain up to three characters.
The name must start with either a letter or number. It can contain any uppercase or lowercase (filenames are not case-sensitive) characters except the following:
period (.) quotation mark (")
slash (/) backslash (\)
brackets ([ ]) colon (:)
semicolon (;) vertical bar (|)
equal sign (=) comma (,)
The name should not contain any spaces. The following names are reserved and cannot be used for files or directories: CON, AUX, COM1, COM2, COM3, COM4, LPT1, LPT2, LPT3, PRN, and NUL. Examples of valid filenames are LETTER.DOC, MEMO.TXT, BUDGET.92, 12345678.901 and 2NDTRY.RPT.