If you are writing about computer science, or more general scientific or engineering topics, you may wish to include sample computer programs, or command-line sessions. A <program> will contain a complete computer program, or a portion of the code from a program. Some <program> can execute in an online output format, while others are both editable and executable. This behavior depends on the language used and the host employed. A <console> holds a command-line session. These elements feature monospace fonts, preservation of whitespace, and syntax highlighting. These may also be placed in a <listing> to be more prominent, or as the target of a cross-reference. See Section 4.15 for details.