This OCTET STRING gives the hardware revision of the chassis written out as text, and the MIB says it should be used instead of the plain-integer HardwareRevision object whenever the OEM VPD area has this string programmed. An admin relies on the string form to avoid ambiguity, since a numeric revision code alone can't capture vendor-specific revision letters or suffixes. For example, if chassisHardwareRevision alone returns an ambiguous integer, an admin reads chassisHardwareRevisionString to see the full vendor revision text, such as a lettered suffix, printed in the OEM VPD area.