Basic introduction about SAP SPS (Support Package Stack)

You can search out the related support package stack here in PAM (Product Availability Matrix) , e.g. CRM.

https://apps.support.sap.com/sap(bD1lbiZjPTAwMQ==)/support/pam/pam.html?smpsrv=https%3A%2F%2Fwebsmp102.sap-ag.de#ts=12

Then you can select the product version you are looking for and go to the details. E.g. EHP4 FOR SAP CRM 7.0. Then you can see all the SPS information for this production version.

If click the details link, then you can see the dedicated release information note for this specific SPS.