\include{file}
The \include command is used in conjunction with the
\includeonly command for selective inclusion of files. The
file argument is the first name of a file, denoting
`file.tex'. If file is one the file names in the file list
of the \includeonly command or if there is no \includeonly
command, the \include command is equivalent to
\clearpage \input{file} \clearpage
except that if the file `file.tex' does not exist, then a warning
message rather than an error is produced. If the file is not in the
file list, the \include command is equivalent to \clearpage.
The \include command may not appear in the preamble or in a file
read by another \include command.