+But it is not recommended to use them for test selection,
+as it is not that easy to determine how many test cases are selected.
+
+The recommended way is to look into CSIT repository first,
+and locate a specific suite the user is interested in,
+and use its suite tag. For example, "ethip4-ip4base" is a suite tag
+selecting just one suite in CSIT git repository,
+avoiding all scale, container, and other simialr variants.
+
+Note that CSIT uses "autogen" code generator,
+so the robot running in Jenkins has access to more suites
+than visible just by looking into CSIT git repository,
+so suite tag is not enough to select even the intended suite,
+and user still probably wants to narrow down
+to a single test case within a suite.
+
+Fully specified tag expressions
+_______________________________
+
+Here is one template to select a single test case:
+{test_type}AND{nic_model}AND{nic_driver}AND{cores}AND{frame_size}AND{suite_tag}
+where the variables are all lower case (so AND operator stands out).
+
+Currently only one test type is supported by the performance comparison jobs:
+"mrr".
+The nic_driver options depend on nic_model. For Intel cards "drv_avf" (AVF plugin)
+and "drv_vfio_pci" (DPDK plugin) are popular, for Mellanox "drv_rdma_core".
+Currently, the performance using "drv_af_xdp" is not reliable enough, so do not use it
+unless you are specifically testing for AF_XDP.
+
+The most popular nic_model is "nic_intel-xxv710", but that is not available
+on all testbed types.
+It is safe to use "1c" for cores (unless you are suspection multi-core performance
+is affected differently) and "64b" for frame size ("78b" for ip6
+and more for dot1q and other encapsulated traffic;
+"1518b" is popular for ipsec and other payload-bound tests).
+
+As there are more test cases than CSIT can periodically test,
+it is possible to encounter an old test case that currently fails.
+To avoid that, you can look at "job spec" files we use for periodic testing,
+for example `this one <https://github.com/FDio/csit/blob/master/docs/job_specs/report_iterative/2n-skx/vpp-mrr-00.md>`_.
+
+..
+ TODO: Explain why "periodic" job spec link lands at report_iterative.
+
+Shortening triggers
+___________________
+
+Advanced users may use the following tricks to avoid writing long trigger comments.
+
+Robot supports glob matching, which can be used to select multiple suite tags at once.
+
+Not specifying one of 6 parts of the recommended expression pattern
+will select all available options. For example not specifying nic_driver
+for nic_intel-xxv710 will select all 3 applicable drivers.
+You can use NOT operator to reject some options (e.g. NOTdrv_af_xdp),
+but beware, with NOT the order matters:
+tag1ANDtag2NOTtag3 is not the same as tag1NOTtag3ANDtag2,
+the latter is evaluated as tag1AND(NOT(tag3ANDtag2)).
+
+Beware when not specifying nic_model. As a precaution,
+CSIT code will insert the defailt NIC model for the tetsbed used.
+Example: Specifying drv_rdma_core without specifying nic_model
+will fail, as the default nic_model is nic_intel-xxv710
+which does not support RDMA core driver.
+
+Complete example
+________________
+
+A user wants to test a VPP change which may affect load balance whith bonding.
+Searching tag documentation for "bonding" finds LBOND tag and its variants.
+Searching CSIT git repository (directory tests/) finds 8 suite files,
+all suited only for 3-node testbeds.
+All suites are using vhost, but differ by the forwarding app inside VM
+(DPDK or VPP), by the forwarding mode of VPP acting as host level vswitch
+(MAC learning or cross connect), and by the number of DUT1-DUT2 links
+available (1 or 2).
+
+As not all NICs and testbeds offer enogh ports for 2 parallel DUT-DUT links,
+the user looks at `testbed specifications <https://github.com/FDio/csit/tree/master/topologies/available>`_
+and finds that only x710 NIC on 3n-skx testbed matches the requirements.
+Quick look into the suites confirm the smallest frame size is 64 bytes
+(despite DOT1Q robot tag, as the encapsulation does not happen on TG-DUT links).
+It is ok to use just 1 physical core, as 3n-skx has hyperthreading enabled,
+so VPP vswitch will use 2 worker threads.
+
+The user decides the vswitch forwarding mode is not important
+(so choses cross connect as that has less CPU overhead),
+but wants to test both NIC drivers (not AF_XDP), both apps in VM,
+and both 1 and 2 parallel links.
+
+After shortening, this is the trigger comment fianlly used:
+perftest-3n-skx mrrANDnic_intel-x710AND1cAND64bAND?lbvpplacp-dot1q-l2xcbase-eth-2vhostvr1024-1vm*NOTdrv_af_xdp
+