hi
you could use the remember trigger for this, name sp_market_id , with the condition
and selections (back/lay you didn't say which) matched is greater than 0
set the trigger to in-play , because the sp is only formed at in-play
then you can look or use the info like
sp_market_id_1_sel_name
sp_market_id_1_acutal_sp
this gives the name and sp for the first selection, then you use 2 and 3 etc in place of the 1
mcbee