Users often supply file names as part of an application's command line or in response to a prompt from the application. Traditionally, users have been able to supply more than one file name by separating the names with certain characters, such as a blank space. In some file systems, however, traditional separators are valid file name characters. This means additional conventions are required to ensure that an application processes all characters in a name.

When an application processes arguments (including file names) from its command line, the operating system treats the double quotation mark (") and the caret (^) as quotation characters. All characters between the opening and closing double quotation marks are processed as a single argument. The caret is used to quote characters that would otherwise have some special property. The character immediately following the caret is treated as a normal character; any special characteristics that the character has are to be ignored. For example, the greater-than symbol (>) normally causes a program's output to be redirected to a file or device. Typing "^>" causes the ">" to be included in the command line passed to the application. In both cases, the operating system discards the quotation characters and does not treat them as part of the final argument.

When a Presentation Manager*(PM) application processes two or more file names from a dialog box or other prompt, it expects the user to enter each file name on a new line. Therefore, a PM application would use a multiple-line entry field to prompt for multiple file names. This often makes the use of quotation characters unnecessary.

When an application is started, the operating system constructs a command line for the application. If the command line includes file names, the operating system places a space character between names and marks the end of the list with two NULL characters. Applications that start other applications by using DosExecPgm can also pass arguments by using this convention or by using quotation characters. In practice, most applications receive a command line as a single, NULL-terminated string. Therefore, applications that use DosExecPgm should prepare command lines as a single string, and enclose any file names in quotation marks.