In reply to mayurkubavat:
Hi Mayur,
It looks like using a null sequencer alters the hierarchy of the sequence.
If I use reg_type_b_seq.start(env.agt.sqr), the result is:
Sequence hierarchy: uvm_test_top.env.agt.sqr.reg_type_b_seq
If I use reg_type_b_seq.start(null), the result is:
Sequence hierarchy: reg_type_b_seq
Notice that it removes all the higher hierarchies.