- Entry:
- TREM, TRED, TREI, or TREB
- VIT option:
- SSCP
- Event:
- Routing tree Build or Update
- VIT processing module:
- ISTRACSC
- Control is returned to:
- Module invoking the INTRACE macro that caused the record to be produced
A routing tree operations (TRE) VIT entry is created by
topology and routing services (TRS) whenever one of the following
events is encountered: 
- TRS accesses or builds a routing tree to satisfy a request for an APPN route.
- An existing routing tree is marked for modification because of a topological change in the APPN network.
- TRS learns of the availability or loss of a central directory server or interchange node.
- Byte (hex)
- 00–03
- Record ID:
- C'TREM'
- Mark tree.
- C'TRED'
- Add or change directory server.
- C'TREI'
- Add or change interchange node.
- C'TREB'
- Build tree.
- 04
- ID is the primary address space ID (ASID). This field is 0 if the ASID is greater than X'FF'.
- 05
- Tree marking flags
- Bit
- Meaning
- x... ....
-
1 = Operable resource state
0 = Inoperable resource state - .xxx ....
- 0
- .... xxxx
- Reason
0000 = Transmission group update
0001 = Topology database update
0010 = Garbage collection
0011 = Overuse
0100 = Modify topology
0101 = Database reset
0110 = Uncache tree
0111 = Unreachable partner change
1000 = Unacceptable hop detected
- 06
- Indicates that a directory server or interchange node is added ("A") or deleted ("D")
- 07
- Tree building flags
- Bit
- Meaning
- x... ....
- Indicates whether existing tree is used
1 = Existing tree is used.
0 = New tree is built; existing tree is not available. - .x.. ....
- Indicates whether clean path is used.
1 = Clean path is used.
0 = Clean path is not available. - ..x. ....
- Indicates number of destinations
1 = Multiple
0 = Single
- 08–0B
- Path weight, resource sequence number, or topology database node
pointer, depending on entry type and flags:
- Entry type
- Meaning
- B
- Path weight
- M
-
- If tree marking flags are ('1000'), topology database node pointer associated with the unacceptable tree record
- Otherwise, resource sequence number
Note: If entry type is TREB and the destination tree record pointer indicates multiple destinations, the path weight field is not valid. - 0C–0F
- Tree header pointer or topology database resource pointer, depending
on entry type and flags:
- Entry type
- Meaning
- B
- Tree header pointer
- M
-
- If tree marking flags are ('1000'), tree header pointer
- Otherwise, topology database resource pointer
- 10–13
- Return address of caller
- 14–17
- Origin tree record pointer or CoS pointer, depending on entry
type and flags:
- Entry type
- Meaning
- B
- Origin tree record pointer
- M
-
- If tree marking flags are ('1000'), origin tree record pointer
- If tree marking flags are ('0110'), CoS pointer
- 18–1B
- Destination tree record pointer, unacceptable tree record pointer,
or calling module, depending on entry type and flags:
- Entry type
- Meaning
- B
- Destination tree record pointer
- M
-
- If tree marking flags are ('1000'), unacceptable tree record pointer
- If tree marking flags are ('0110'), last four characters of calling module name
- 1C–1F
- Tree building execution time (microseconds), if entry type is B