mention possibility of pubkey on nevent.

19.md

@@ -46,14 +46,14 @@ These possible standardized `TLV` types are indicated here:
     - for `nrelay`, this is the relay URL
     - for `naddr`, it is the identifier (the `"d"` tag) of the event being referenced
 - `1`: `relay`
-  - for `nprofile`, `nevent` and `naddr`, a relay in which the entity (profile or event) is more likely to be found, encoded as ascii
+  - for `nprofile`, `nevent` and `naddr`, _optionally_, a relay in which the entity (profile or event) is more likely to be found, encoded as ascii
   - this may be included multiple times
 - `2`: `author`
   - for `naddr`, the 32 bytes of the pubkey of the event
+  - for `nevent`, _optionally_, the 32 bytes of the pubkey of the event
 - `3`: `kind`
   - for `naddr`, the 32-bit unsigned integer of the kind, big-endian
 
-
 ## Examples
 
 - `npub10elfcs4fr0l0r8af98jlmgdh9c8tcxjvz9qkw038js35mp4dma8qzvjptg` should decode into the public key hex `7e7e9c42a91bfef19fa929e5fda1b72e0ebc1a4c1141673e2794234d86addf4e` and vice-versa