A block in the chain for a LOCATE command search is not a valid index block. The following tests are made for a valid index block:

• The same tests are made as shown for message IRR63012I.
• The RBA (relative byte address) for the next byte on the chain must be nonzero, with the two high-order bytes zero, and represent an address on a 4K boundary within the extent of the RACF® database.
• The level of the block must be below the level of the previous block on the chain.