The format of the TRACE statement is:
TRACE [MINOR=minorcode,]
TP={@STATIC,|@filename,linenum,|.name[{+|-}offs][,RETEP[=retopt[+retopt...]]]},
[OPCODE=0xnn,]
[TYPE=(typename[,typename...]),]
[GROUP=groupnam,]
[DESC="Tracepoint description",]
[FMT="Formatting string",]...
[LEN=(length_spec,flag),]
[DATA_STMT,]...
The TRACE keyword delimits a tracepoint definition statement. The definition is considered complete when the next TRACE keyword is encountered or the end of file is reached. There is one TRACE statement for each tracepoint.
LEN is used to log variable length records. A DATA_STMT must immediately follow the LEN statement. LEN will give the location of a one word field containing the number of bytes to log for the following DATA_STMT.