The hyphen-minus character is also often used when specifying command-line options. The character is usually followed by one or more letters that indicate specific actions. Typically it is called a dash or switch in this context. Various implementations of the getopt function to parse command-line options additionally allow the use of two hyphen-minus characters, , to specify long option names that are more descriptive than their single-letter equivalents. Another use of hyphens is that employed by programs written with pipelining in mind: a single hyphen may be recognized of a filename, with the hyphen then serving as an indicator that a standard stream, instead of a file, is to be worked with.