This summary is not the rule. The rule text controls.
When someone files an affidavit to support or fight a summary judgment motion, that affidavit has to follow certain rules. The person signing it must be writing about things they actually know firsthand, not rumors or guesses. Everything stated in the affidavit has to be the kind of information that would be allowed as evidence in court. The affidavit also needs to make clear that the person signing it is actually qualified to talk about these facts, meaning they have the right knowledge or experience to back up what they're saying.
If the affidavit mentions other documents, like contracts, letters, or records, copies of those documents need to be attached to the affidavit or turned in along with it. These copies must be sworn to or certified as accurate.
Finally, the court has some flexibility here. If more information is needed, the court can allow people to add to their affidavits or challenge them using depositions (recorded testimony taken outside of court) or additional affidavits. This gives both sides a chance to present a full and fair picture before the court decides whether to grant summary judgment.