Sequences can be grouped using uvm sequence library , sequences can be registered to sequence library using the macro `uvm_add_to_seq_lib(). When the sequence library is started it randomly selects and executes the sequence depending on the selection mode. Selection modes can be any of the following
UVM_SEQ_LIB_RAND -- Random selection of sequence
UVM_SEQ_LIB_RANDC -- Random selection without repeating the sequences
UVM_SEQ_LIB_ITEM -- Execute a single sequence item
UVM_SEQ_LIB_USER -- user selects sequences using select_sequence() method
Selection mode of the sequence library is set using uvm_config_db().
sequence library can be used to create system level scenario using random sequences.