PEP 656: Minor clarification on relation to PEP 600 (#1911)

pep-0656.rst

@@ -42,9 +42,10 @@ run against a newer musl runtime [musl-compat-ml]_. Therefore, we use
 a scheme similar to the glibc-version-based manylinux tags, but
 against musl versions instead of glibc.
 
-Logic behind the new platform tag largely follows :pep:`600`, and
-require wheels using this tag make similar promises. Please refer to
-the PEP for more details on rationale and reasoning behind the design.
+Logic behind the new platform tag largely follows :pep:`600`
+("perennial manylinux"), and requires wheels using this tag make
+similar promises. Please refer to :pep:`600` for more details on
+rationale and reasoning behind the design.
 
 The ``musllinux`` platform tags only apply to Python interpreters
 dynamically linked against the musl libc and executed on the runtime
@@ -62,6 +63,18 @@ Tags using the new scheme will take the form::
 
     musllinux_${MUSLMAJOR}_${MUSLMINOR}_${ARCH}
 
+This tag promises the wheel works on any mainstream Linux distribution
+that uses musl version ``${MUSLMAJOR}.${MUSLMINOR}``, following the
+perennial design. All other system-level dependency requirements rely
+on the community's definition to the intentionally vague "mainstream"
+description introduced in :pep:`600`. A wheel may make use of newer
+system dependencies when all mainstream distributions using the
+specified musl version provide the dependency by default; once all
+mainstream distributions on the musl version ship a certain dependency
+version by default, users relying on older versions are automatically
+removed from the coverage of that ``musllinux`` tag.
+
+
 Reading the musl version
 ------------------------