A sequencing reality check.

Continuation of application No. 09/362,089, filed on Jul. 28, 1999, which is a division of application No. 09/056,927, filed on Apr. 8, 1998, now Pat. No. 6,197.506, which is a continuation of application No. 08/670,118, filed on Jun. 25, 1996, now Pat. No. 5,800,992, which is a division of application No. 08/168.904, filed on Dec. 15, 1993, now abandoned, which is a continuation of application No. 07/624,114, filed on Dec. 6, 1990, now abandoned, which is a continuation-in-part of application No. 07/492,462, filed on Mar. 7, 1990, now Pat. No. 5,143,854, which is a continuation-in-part of application No. 07/362,901, filed on Jun. 7, 1989, now abandoned.