||Closes a text file
||CLOSE(texthandle : INTEGER) : INTEGER
||texthandle : text handle from RESET, REWRITE or TAPPEND
0 = successfully closed
External text files are buffered by the tdbengine and mostly by the operating system.
Only the CLOSE makes sure that the file is transmitted and the reservated system resources are freed again.
After CLOSE no access to the text handle is allowed.
Also ramtexts should be closed after use.