When to use /rc vs useRcBlock=true for Relay Chain data?

[Imod7]

Consider these two equivalent endpoints for accessing Relay Chain staking data:

Option 1: /rc prefix

/rc/pallets/Staking/storage/ErasStakersPaged?at=27587098&keys[]=9644&keys[]=5HNPNNpzmcko3azyoVEoVnBCKcevXMJWuwQn5hskbGLC2RHa&keys[]=1

Option 2: useRcBlock=true parameter

/pallets/Staking/storage/ErasStakersPaged?at=27587098&keys[]=9644&keys[]=5HNPNNpzmcko3azyoVEoVnBCKcevXMJWuwQn5hskbGLC2RHa&keys[]=1&useRcBlock=true

Questions:

• What are the practical differences between using the /rc prefix versus the useRcBlock=true parameter?
• In which scenarios would I choose one approach over the other?
• Why is Staking pallet data still accessible through an Asset Hub Westend node? I expected this Relay Chain data to be unavailable after the migration.

This is being queried through an Asset Hub Westend connected node.

[Imod7]

Here's the key distinction:

/rc endpoint:

• Accesses data directly from the Relay Chain
• Pre-migration: Returns staking information (since it existed on Relay Chain)
• Post-migration: Returns empty responses for staking queries (since staking moved to Asset Hub)

useRcBlock=true parameter:

• Accesses Asset Hub data using Relay Chain block numbering for continuity
• Pre-migration: Returns empty/error responses for staking (since Asset Hub didn't handle staking yet)
• Post-migration: Returns current staking state from Asset Hub, mapped to the corresponding Relay Chain block number

When to use each:

• For pre-migration staking data → Use /rc/
• For post-migration staking data with RC block references → Use useRcBlock=true

This design maintains backward compatibility by allowing you to query staking information using familiar Relay Chain block numbers, even though the data now lives on Asset Hub.