The record-type definitions of SRFI 9, R7RS, SRFI 99, SRFI 131, and SRFI
136 are all similar in shape. In particular, they bind an record-type
descriptor.

In order to subtype record-type definitions made by either of these
specifications such that the subtypes are subtypes in the sense of SRFI
137, this SRFI 137 should define an interface that is to be implemented
by record-type descriptors on systems supporting SRFI 137 that gives
access to the (underlying/emulated) SRFI 137 interface of the record-type.

For example, SRFI 137 could specify a syntax ’type’ such that (type
<rtd>) would expand into the five values of the (underlying/emulated)
’make-type’ that was evaluated during creation of the record-type.

Marc