If rules are hidden

then

rule identifiers are shown in lowercase letters and on yellow background:

hide 02 01
 

then

the number of filtered rules is presented in the tool tip for rule identifier:

hide 02 02
 

then

all rows which are not filled out in this view (here: C06, A02 and A03) can also be hidden. See also hiding and showing empty rows:

hide 03 01