Hi,
The page tab in purchase requisition or purchase order will be based on activating the business function
LOG_EAM_ROTSUB and AD_MRO_CI_3.
For more information kindly refer the below help doc it may help you.
http://help.sap.com/erp2005_ehp_04/helpdata/EN/bc/5bba42a75fc611e10000000a1550b0/content.htm