Clarify DID are strings

README.md

@@ -49,17 +49,17 @@ The UCAN envelope tag for UCAN Delegation MUST be set to `ucan/[email protected]`.
 
 The Delegation payload MUST describe the authorization claims, who is involved, and its validity period.
 
-| Field | Type | Required | Description |
-|---------|-------------------------------------------|----------|-------------------------------------------------------------|
-| `iss` | `DID` | Yes | Issuer DID (sender)  |
-| `aud` | `DID` | Yes | Audience DID (receiver) |
-| `sub` | `DID \| null` | Yes | Principal that the chain is about (the [Subject]) |
-| `cmd` | `String` | Yes | The [Command] to eventually invoke |
-| `pol` | `Policy` | Yes | [Policy] |
-| `nonce` | `Bytes` | Yes | Nonce |
-| `meta` | `{String : Any}` | No | [Meta] (asserted, signed data) — is not delegated authority |
-| `nbf` | `Integer` (53-bits[^js-num-size]) | No | "Not before" UTC Unix Timestamp in seconds (valid from) |
-| `exp` | `Integer \| null` (53-bits[^js-num-size]) | Yes | Expiration UTC Unix Timestamp in seconds (valid until) |
+| Field | Type | Required | Description  |
+|---------|-------------------------------------------|----------|---------------------------------------------------------------------------|
+| `iss` | `DID` | Yes | Issuer DID (sender). All [DID][did-spec]s are represented as string URLs. |
+| `aud` | `DID` | Yes | Audience DID (receiver)  |
+| `sub` | `DID \| null` | Yes | Principal that the chain is about (the [Subject])  |
+| `cmd` | `String` | Yes | The [Command] to eventually invoke  |
+| `pol` | `Policy` | Yes | [Policy]  |
+| `nonce` | `Bytes` | Yes | Nonce  |
+| `meta` | `{String : Any}` | No | [Meta] (asserted, signed data) — is not delegated authority  |
+| `nbf` | `Integer` (53-bits[^js-num-size]) | No | "Not before" UTC Unix Timestamp in seconds (valid from)  |
+| `exp` | `Integer \| null` (53-bits[^js-num-size]) | Yes | Expiration UTC Unix Timestamp in seconds (valid until)  |
 
 [^js-num-size]: JavaScript has a single numeric type ([`Number`][JS Number]) for both integers and floats. This representation is defined as a [IEEE-754] double-precision floating point number, which has a 53-bit significand.
 
@@ -201,20 +201,6 @@ Policies are structured as trees. With the exception of subtrees under `any`, `o
 
 A Policy is an array of statements. Every statement MUST take the form `[operator, selector, argument]` except for negation which MUST take the form `["not", statement]`.
 
-Below is a formal syntax for the UCAN Policy Language given in [ABNF] (representing IPLD as [DAG-JSON]):
-
-``` abnf
-selector = DQUOTE "." DQUOTE ; Identity
- / DQUOTE 1*(subselector *1("?")) DQUOTE ; Nested subselectors with possible optionals
-
-subselector = "." CHAR string ; Dotted field selector
- / *1(".") "[\" DQUOTE string "\" DQUOTE "]" ; Explicit field selector
- / *1(".") "[" integer "]" ; Index selector
- / *1(".") "[]" ; Collection values // FIXME doble check code
-```
-
-
-
 ``` ipldsch
 -- Statements
 
@@ -954,6 +940,7 @@ We want to especially recognize [Mark Miller] for his numerous contributions to
 [`did:web`]: https://w3c-ccg.github.io/did-method-web/
 [base32]: https://github.com/multiformats/multibase/blob/master/multibase.csv#L13
 [dag-json multicodec]: https://github.com/multiformats/multicodec/blob/master/table.csv#L112
+[did-spec]: https://www.w3.org/TR/did-core/
 [did:key ECDSA]: https://w3c-ccg.github.io/did-method-key/#p-256
 [did:key EdDSA]: https://w3c-ccg.github.io/did-method-key/#ed25519-x25519
 [did:key RSA]: https://w3c-ccg.github.io/did-method-key/#rsa