- Fix section levels

- Add Message Interaction Details + new mimetypes

bip-invoicerequest-extension.mediawiki

@@ -32,7 +32,7 @@ to facilitate identification for address release.
 | Receiver  || Entity receiving a value transfer
 |}
 
-===Acronyms===
+==Acronyms==
 {| class="wikitable"
 ! Acronym !! Expanded !! Description
 |-
@@ -41,9 +41,9 @@ to facilitate identification for address release.
 | RPR || ReturnPaymentRequest  || A ReturnPaymentRequest returned based on a submitted InvoiceRequest
 |}
 
-===New Messages===
+==New Messages==
 
-====InvoiceRequest====
+===InvoiceRequest===
 The new InvoiceRequest message allows a requestor to send information to the responder such that they can return a ReturnPaymentRequest.
 
 <pre>
@@ -68,12 +68,12 @@ message InvoiceRequest {
 |-
 | pki_data              || Depends on pki_type
 |-
-| notification_url      || URL to notify on ReturnPaymentRequest ready
+| notification_url      || Secure (usually HTTPS) location where a ReturnPaymentRequest (see below) may be sent when ready
 |-
 | signature             || PKI-dependent signature
 |}
 
-====ReturnPaymentRequest====
+===ReturnPaymentRequest===
 
 The new ReturnPaymentRequest message is an encapsulating message that allows the transmission of an encrypted, serialized PaymentRequest.
 
@@ -111,12 +111,28 @@ The new ReturnPaymentRequest message is an encapsulating message that allows the
 # Sender validates ReturnPaymentRequest
 # Sender decrypts and validates encrypted PaymentRequest
 
+===Message Interaction Details===
+
+====InvoiceRequest====
+Sender must transmit InvoiceRequest to Receiver (or Receiver's agent) via TLS-protected HTTP. Sender transmitting InvoiceRequest 
+messages must set appropriate Content-Type headers as specified here:
+<pre>Content-Type: application/bitcoin-invoicerequest</pre>
+
+====ReturnPaymentRequest====
+Receiver must transmit ReturnPaymentRequest to Sender (or Sender's agent) via TLS-protected HTTP. Receiver transmitting
+ReturnPaymentRequest messages must set appropritate Content-Type headers as specified here:
+<pre>Content-Type: application/bitcoin-returnpaymentrequest</pre>
+
+====Message or Communication Errors====
+An invalid or unparsable message or communications error must be communicated to the party that initiated the communication. This
+should be done through standard HTTP Status Code messaging ([https://tools.ietf.org/html/rfc7231 RFC 7231 Section 6]).
+
 ===InvoiceRequest Message Creation===
 
 * Create an InvoiceRequest message
-* sender_public_key MUST be set. This is the public key of an EC keypair using secp256k1.
-* Set amount if desired
-* Set notification_url to URL that Receiver will submit completed ReturnPaymentRequest to
+* sender_public_key MUST be set to the public key of an EC keypair.
+* Amount is optional
+* Set notification_url to URL that the Receiver will submit completed ReturnPaymentRequest to
 * If NOT including certificate, set pki_type to "none"
 * If including certificate:
 ** Set pki_type to "x509+sha256"