inconsistent references for HKDF-CTR

https://www.w3.org/Bugs/Public/show_bug.cgi?id=24838

HKDF-CTR references RFC5869, NIST SP800-56C and NIST SP800-108.

These references specify different algorithms.

RFC5869 calculates output keying material as the concatenation of T(i)
i=1, ..., N where T(i) = HMAC-Hash(PRK, T(i-1) | info | [i] ) where
PRK is a key derived from the base key through an extraction step and
[i] is a single octet representation of i.

By contrast, SP800-108 calculates the output keying material as the
concatenation of K(i) i=1,...,N where K(i) := PRF(KI, [i] || Label ||
0x00 || Context || [L] ) where KI is the key derivation key and [L] is
the binary representation of the number of output bits.

Which reference should we use, or should we support both as separate
algorithms ?

...Mark