Invoking STRAT will allow you to assign strata to the pairs in the section. You may enter strata sequentially by pressing the F6 key or use the arrow keys and select the pairs to designate by pressing Enter key. Pressing the F9 key will save the information.
If the section is manually scored, you can use STRAT to also specify stratum field sizes. You would want to do this if you entered only the names and scores for the players which ranked. Useful for the DIC of a STAC for reports from clubs which do not use ACBLscore.