[SOLVED] Is there a spec for CSR 'BEGIN' headers?

I've noticed a subtle difference in how OpenSSL and Microsoft certreq generate PKCS10 CSRs:

OpenSSL:
```
  -----BEGIN CERTIFICATE REQUEST-----
```

Microsoft certreq:

  -----BEGIN NEW CERTIFICATE REQUEST-----

(and a footer with the same, except for END)

The PKCS10 spec doesn't have any information on these headers / footers, so I suspect they're not part of the spec. I would like to be able to handle as many formats of CSRs as possible, so:

Is there a spec for CSRs 'BEGIN' headers?

Also: do other forms of CSR header exist? What do CSR generation tools that aren't openssl or certreq use?