as spotted by dotneft.

2.2 added a very nice ability to extract values in log/logrt items. documentation in some places is missing.
whatsnew has nice overview at https://www.zabbix.com/documentation/2.2/manual/introduction/whatsnew220#ability_to_extract_matching_part_of_a_regular_expression

a) these details (and more) should be added to https://www.zabbix.com/documentation/2.2/manual/config/items/itemtypes/log_items
b) 'output' is missing for log, logrt, vfs.file.regexp and web.page.regexp keys in https://www.zabbix.com/documentation/2.2/manual/appendix/items/supported_by_platform
c) (realistic) examples should be added to https://www.zabbix.com/documentation/2.2/manual/config/items/itemtypes/zabbix_agent