Suggested replacement text for the two paragraphs:
Vendor RADIUS Attribute specifications SHOULD allocate attributes
from the vendor space, rather than requesting an allocation from the
RADIUS standard attribute space. Vendors are reminded that
allocations from the standard space MUST follow the process described
in [RFC3575] Section 2.1. Vendor RADIUS Attribute specifications
MUST NOT allocate attributes with vendor-specific meaning from the
standard space (i.e. attributes 1 through 255). Uncoordinated
allocations from the standard space would prevent inter-operation
with later standards that follow the IETF process.
...
Vendors SHOULD NOT allocate new values for attributes of enumerated
type (e.g. Service-Type), despite the Vendor Specific Enumerations
proposal in [RFC2882] Section 2.2.1. Such allocations may only be
performed under the guidelines of [RFC3575] Section 2.1. Instead,
vendors SHOULD allocate an attribute from their Vendor-Specific
space, and define an appropriate value for it.