diff --git a/datastore/protobuf/datastore.proto b/datastore/protobuf/datastore.proto
index 98ab8e7..eb920dc 100644
--- a/datastore/protobuf/datastore.proto
+++ b/datastore/protobuf/datastore.proto
@@ -72,37 +72,38 @@ message Link {
 }
 
 message TSMetadata {
-  // --- BEGIN metadata of type 'single string' -----------------
-  string version = 1;
-  string type = 2;
-  string title = 3;
-  string summary = 4;
-  string keywords = 5;
-  string keywords_vocabulary = 6 [json_name = "keywords_vocabulary"];
-  string license = 7;
-  string conventions = 8;
-  string naming_authority = 9 [json_name = "naming_authority"];
-  string creator_type = 10 [json_name = "creator_type"];
-  string creator_name = 11 [json_name = "creator_name"];
-  string creator_email = 12 [json_name = "creator_email"];
-  string creator_url = 13 [json_name = "creator_url"];
-  string institution = 14;
-  string project = 15;
-  string source = 16;
-  string platform = 17;
-  string platform_vocabulary = 18 [json_name = "platform_vocabulary"];
-  string standard_name = 19 [json_name = "standard_name"];
-  string unit = 20;
-  string instrument = 21;
-  string instrument_vocabulary = 22 [json_name = "instrument_vocabulary"];
-  // --- END metadata of type 'single string' -----------------
-
-  // --- BEGIN metadata of other type -----------------
-  repeated Link links = 23;
-  // --- END metadata of other type -----------------
+  // --- BEGIN non-string metadata -----------------
+  repeated Link links = 1;
+  // --- END non-string metadata -----------------
+
+  // --- BEGIN string metadata -----------------
+  string version = 2;
+  string type = 3;
+  string title = 4;
+  string summary = 5;
+  string keywords = 6;
+  string keywords_vocabulary = 7 [json_name = "keywords_vocabulary"];
+  string license = 8;
+  string conventions = 9;
+  string naming_authority = 10 [json_name = "naming_authority"];
+  string creator_type = 101 [json_name = "creator_type"];
+  string creator_name = 12 [json_name = "creator_name"];
+  string creator_email = 13 [json_name = "creator_email"];
+  string creator_url = 14 [json_name = "creator_url"];
+  string institution = 15;
+  string project = 16;
+  string source = 17;
+  string platform = 18;
+  string platform_vocabulary = 19 [json_name = "platform_vocabulary"];
+  string standard_name = 20 [json_name = "standard_name"];
+  string unit = 21;
+  string instrument = 22;
+  string instrument_vocabulary = 23 [json_name = "instrument_vocabulary"];
+  // --- END string metadata -----------------
 }
 
 message ObsMetadata {
+  // --- BEGIN non-string metadata -----------------
   oneof geometry {
     Point geo_point = 1 [json_name = "geo_point"];
     Polygon geo_polygon = 2 [json_name = "geo_polygon"];
@@ -112,16 +113,17 @@ message ObsMetadata {
     //TimeInterval obstime_interval = 4 [json_name = "obstime_interval"]; -- unsupported for now
   }
   google.protobuf.Timestamp pubtime = 5;
+  // --- END non-string metadata -----------------
 
-  // --- BEGIN metadata of type 'single string' -----------------
+  // --- BEGIN string metadata -----------------
   string id = 6;
   string data_id = 7 [json_name = "data_id"];
   string history = 8;
   string metadata_id = 9 [json_name = "metadata_id"];
   string processing_level = 10 [json_name = "processing_level"];
-  // --- END metadata of type 'single string' -----------------
+  // --- END string metadata -----------------
 
-  string value = 11; // obs value
+  string value = 11; // obs value (not metadata in a strict sense)
 }
 
 //---------------------------------------------------------------------------
diff --git a/datastore/storagebackend/postgresql/postgresql.go b/datastore/storagebackend/postgresql/postgresql.go
index 4b7bdb5..78f1049 100644
--- a/datastore/storagebackend/postgresql/postgresql.go
+++ b/datastore/storagebackend/postgresql/postgresql.go
@@ -94,13 +94,15 @@ func NewPostgreSQL() (*PostgreSQL, error) {
 func getTSMdataCols() []string {
 	// ### TODO: modify to use reflection instead of explicit field referrals
 	return []string{
-		// links section (aka. non-string metadata ...)
+		// --- BEGIN non-string metadata ---------------------------
 		"link_href",
 		"link_rel",
 		"link_type",
 		"link_hreflang",
 		"link_title",
-		// main section (aka. string metadata ...)
+		// --- END non-string metadata ---------------------------
+
+		// --- BEGIN string metadata ---------------------------
 		"version",
 		"type",
 		"title",
@@ -123,6 +125,7 @@ func getTSMdataCols() []string {
 		"unit",
 		"instrument",
 		"instrument_vocabulary",
+		// --- END string metadata ---------------------------
 	}
 }
 
diff --git a/datastore/storagebackend/postgresql/putobservations.go b/datastore/storagebackend/postgresql/putobservations.go
index 474c315..8225a11 100644
--- a/datastore/storagebackend/postgresql/putobservations.go
+++ b/datastore/storagebackend/postgresql/putobservations.go
@@ -44,7 +44,7 @@ func getTSColVals(tsMdata *datastore.TSMetadata) ([]interface{}, error) {
 
 	colVals := []interface{}{}
 
-	// links section (aka. non-string metadata ...)
+	// --- BEGIN non-string metadata ---------------------------
 
 	getLinkVals := func(key string) ([]string, error) {
 		linkVals := []string{}
@@ -77,7 +77,9 @@ func getTSColVals(tsMdata *datastore.TSMetadata) ([]interface{}, error) {
 		}
 	}
 
-	// main section (aka. string metadata ...)
+	// --- END non-string metadata ---------------------------
+
+	// --- BEGIN string metadata ---------------------------
 
 	// ### TODO: modify to use reflection instead of explicit field referrals
 
@@ -106,6 +108,8 @@ func getTSColVals(tsMdata *datastore.TSMetadata) ([]interface{}, error) {
 		tsMdata.GetInstrumentVocabulary(),
 	}...)
 
+	// --- END string metadata ---------------------------
+
 	return colVals, nil
 }
 
diff --git a/datastore/ts-init.sql b/datastore/ts-init.sql
index 68f3cb6..063ce61 100644
--- a/datastore/ts-init.sql
+++ b/datastore/ts-init.sql
@@ -5,7 +5,15 @@ CREATE TABLE time_series (
 
 	-- --- BEGIN metadata fields that usually don't vary with obs time ---
 
-	-- --- BEGIN metadata of type 'single string' -----------------
+	-- --- BEGIN non-string metadata -----------------
+	link_href TEXT[],
+	link_rel TEXT[],
+	link_type TEXT[],
+	link_hreflang TEXT[],
+	link_title TEXT[],
+	-- --- END non-string metadata -----------------
+
+	-- --- BEGIN string metadata -----------------
     version TEXT NOT NULL, -- required
     type TEXT NOT NULL, -- required
     title TEXT,
@@ -28,15 +36,8 @@ CREATE TABLE time_series (
     unit TEXT,
 	instrument TEXT NOT NULL,
 	instrument_vocabulary TEXT NOT NULL,
-	-- --- END metadata of type 'single string' -----------------
+	-- --- END string metadata -----------------
 
-	-- --- BEGIN metadata of other type -----------------
-	link_href TEXT[],
-	link_rel TEXT[],
-	link_type TEXT[],
-	link_hreflang TEXT[],
-	link_title TEXT[],
-	-- --- END metadata of other type -----------------
 	-- --- END metadata fields that usually don't vary with obs time ---
 
 	CONSTRAINT unique_main UNIQUE NULLS NOT DISTINCT (version, type, title, summary, keywords,