The message phrase (<msgph>) element contains the text content of a message produced by an application or program. It can also contain the variable name (varname) element to illustrate where variable text content can occur in the message. This element is part of the DITA software domain, a special set of DITA elements designed to document software tasks, concepts and reference information. The message number (<msgnum>) element contains the number of a message produced by an application or program. This element is part of the DITA software domain, a special set of DITA elements designed to document software tasks, concepts and reference information. The variable name (<varname>) element defines a variable that must be supplied to a software application. The variable name element is very similar to the variable (var) element, but variable name is used outside of syntax diagrams, possibly within a message or API description to describe a system variable or environment variable. This element is part of the DITA software domain, a special set of DITA elements designed to document software tasks, concepts and reference information. The message block (<msgblock>) element contains a multi-line message or set of messages. The message block can contain multiple message numbers and message descriptions, each enclosed in a <msgnum> and <msgph> element. It can also contain the message content directly. This element is part of the DITA software domain, a special set of DITA elements designed to document software tasks, concepts and reference information. The command name (<cmdname>) element specifies the name of a command when it is part of a software discussion. This element is part of the DITA software domain, a special set of DITA elements designed to document software tasks, concepts and reference information. The <filepath> element indicates the name and optionally the location of a referenced file by specifying the directory containing the file, and other directories that may precede it in the system hierarchy. This element is part of the DITA software domain, a special set of DITA elements designed to document software tasks, concepts and reference information. The user input (<userinput>) element represens the text a user should input in response to a program or system prompt. This element is part of the DITA software domain, a special set of DITA elements designed to document software tasks, concepts and reference information. The system output (<systemoutput>) element represents computer output or responses to a command or situation. A generalized element, it represents any kind of output from the computer, so the author may wish to choose more specific markup, such as msgph, for messages from the application. The system output element is part of the DITA software domain, a special set of DITA elements designed to document software tasks, concepts and reference information.