update metadata struct comments

neps/nep-0393.md

@@ -264,22 +264,35 @@ All time related attributes are defined in milliseconds (as per NEP-171).
 ```rust
 /// ContractMetadata defines contract wide attributes, which describes the whole contract.
 pub struct ContractMetadata {
-    pub spec: String,              // required, essentially a version like "sbt-1.0.0"
-    pub name: String,              // required, ex. "Mosaics"
-    pub symbol: String,            // required, ex. "MOSAIC"
-    pub icon: Option<String>,      // Data URL
-    pub base_uri: Option<String>, // Centralized gateway known to have reliable access to decentralized storage assets referenced by `reference` or `media` URLs
-    pub reference: Option<String>, // URL to a JSON file with more info
-    pub reference_hash: Option<Base64VecU8>, // Base64-encoded sha256 hash of JSON from reference field. Required if `reference` is included.
+    /// Version with namespace, example: "sbt-1.0.0". Required.
+    pub spec: String,
+    /// Issuer Name, required, ex. "Mosaics"
+    pub name: String,
+    /// Issuer symbol which can be used as a token symbol, eg Ⓝ, ₿, BTC, MOSAIC ...
+    pub symbol: String,
+    /// Icon content (SVG) or a link to an Icon. If it doesn't start with a scheme (eg: https://)
+    /// then `base_uri` should be prepended.
+    pub icon: Option<String>,
+    /// URI prefix which will be prepended to other links which don't start with a scheme
+    /// (eg: ipfs:// or https:// ...).
+    pub base_uri: Option<String>,
+    /// JSON or an URL to a JSON file with more info. If it doesn't start with a scheme
+    /// (eg: https://) then base_uri should be prepended.
+    pub reference: Option<String>,
+    /// Base64-encoded sha256 hash of JSON from reference field. Required if `reference` is included.
+    pub reference_hash: Option<Base64VecU8>,
 }
 
 /// TokenMetadata defines attributes for each SBT token.
 pub struct TokenMetadata {
     pub class: ClassId, // token class. Required. Must be non zero.
-    pub issued_at: Option<u64>, // When token was issued or minted, Unix epoch in milliseconds
-    pub expires_at: Option<u64>, // When token expires, Unix epoch in milliseconds
-    pub reference: Option<String>, // URL to an off-chain JSON file with more info.
-    pub reference_hash: Option<Base64VecU8>, // Base64-encoded sha256 hash of JSON from reference field. Required if `reference` is included.
+    pub issued_at: Option<u64>, // When token was issued or minted, Unix time in milliseconds
+    pub expires_at: Option<u64>, // When token expires, Unix time in milliseconds
+    /// JSON or an URL to a JSON file with more info. If it doesn't start with a scheme
+    /// (eg: https://) then base_uri should be prepended.
+    pub reference: Option<String>,
+    /// Base64-encoded sha256 hash of JSON from reference field. Required if `reference` is included.
+    pub reference_hash: Option<Base64VecU8>,
 }