What these numbers mean in Kannel SMSC logs?

What does these numbers represent ? What does their mean ?

2013-06-27 10:39:42 [9446] [6] DEBUG: SMPP PDU 0x7f8364000a50 dump:

2013-06-27 10:39:42 [9446] [6] DEBUG: type_name: enquire_link

2013-06-27 10:39:42 [9446] [6] DEBUG: command_id: 21 = 0x00000015

2013-06-27 10:39:42 [9446] [6] DEBUG: command_id: 21 = 0x00000015

2013-06-27 10:39:42 [9446] [6] DEBUG: command_status: 0 = 0x00000000

2013-06-27 10:39:42 [9446] [7] DEBUG: SMPP[mvoip]: Got PDU:

2013-06-27 10:39:42 [9446] [6] DEBUG: sequence_number: 519338176 = 0x1ef478c0

2013-06-27 10:39:42 [9446] [6] DEBUG: SMPP PDU dump ends.

They are process (9446) and thread (6,7) identifiers.

For example the bearerbox process starts multiple threads, one for routing, one for communication with the smsbox etc. Normally each smsc will also start at least one thread, some like the http-based drivers starts multiple threads as well.