P20001 is a "container" hot fix that contains "member" hot fixes which will update your SAS software components.
See "What is a container hot fix?" in the SAS Hot Fix FAQ for more information on container and member hot fixes.
A manifest listing the contents of each of the following "member" hot fixes is available:
P23001 manifest for SAS Merchandise Intelligence Client 5.21_M4
P24001 manifest for SAS Merchandise Intelligence Mid-Tier 5.21_M4
P25001 manifest for SAS Merchandise Intelligence Plug-in for SAS Management Console 5.21_M4
P26001 manifest for SAS Merchandise Intelligence Workbench Server 5.21_M4
P27001 manifest for SAS Merchandise Solutions Configuration Workbench 5.21_M4
P28001 manifest for SAS Merchandise Intelligence Grid Server 5.21_M4