diff --git a/meta/antenna.go b/meta/antenna.go
index 5998049ca..dc24363ce 100644
--- a/meta/antenna.go
+++ b/meta/antenna.go
@@ -39,9 +39,9 @@ var InstalledAntennaTable Table = Table{
 	headers: installedAntennaHeaders,
 	primary: []string{"Make", "Model", "Serial", "Mark", "Start Date"},
 	native:  []string{"Height", "North", "East", "Azimuth"},
-	foreign: map[string][]string{
-		"Asset": {"Make", "Model", "Serial"},
-		"Mark":  {"Mark"},
+	foreign: map[string]map[string]string{
+		"Asset": {"Make": "Make", "Model": "Model", "Serial": "Serial"},
+		"Mark":  {"Mark": "Mark"},
 	},
 	remap: map[string]string{
 		"Start Date": "Start",
diff --git a/meta/asset.go b/meta/asset.go
index 0ca1ddebf..ada4f5781 100644
--- a/meta/asset.go
+++ b/meta/asset.go
@@ -29,10 +29,11 @@ var assetHeaders Header = map[string]int{
 }
 
 var AssetTable Table = Table{
-	name:    "Asset",
-	headers: assetHeaders,
-	primary: []string{"Make", "Model", "Serial"},
-	foreign: map[string][]string{},
+	name:     "Asset",
+	headers:  assetHeaders,
+	primary:  []string{"Make", "Model", "Serial"},
+	foreign:  map[string]map[string]string{},
+	nullable: []string{"Notes", "Number"},
 }
 
 type AssetList []Asset
diff --git a/meta/calibration.go b/meta/calibration.go
index e2cc68602..83a248dc7 100644
--- a/meta/calibration.go
+++ b/meta/calibration.go
@@ -41,8 +41,14 @@ var CalibrationTable Table = Table{
 	headers: calibrationHeaders,
 	primary: []string{"Make", "Model", "Serial", "Number", "Start Date"},
 	native:  []string{"Scale Factor", "Scale Bias", "Scale Absolute", "Frequency"},
-	foreign: map[string][]string{
-		"Asset": {"Make", "Model", "Serial"},
+	foreign: map[string]map[string]string{
+		"Asset": {"Make": "Make", "Model": "Model", "Serial": "Serial"},
+	},
+	nullable: []string{"Frequency"},
+	defaults: map[string]string{
+		"Scale Factor":   "1.0",
+		"Scale Absolute": "0.0",
+		"Scale Bias":     "0.0",
 	},
 	remap: map[string]string{
 		"Scale Factor":   "ScaleFactor",
diff --git a/meta/camera.go b/meta/camera.go
index 6b6921ce5..595a7b4ad 100644
--- a/meta/camera.go
+++ b/meta/camera.go
@@ -45,10 +45,11 @@ var InstalledCameraTable Table = Table{
 	headers: installedCameraHeaders,
 	primary: []string{"Make", "Model", "Serial", "Start Date"},
 	native:  []string{"Azimuth", "Dip", "Height", "North", "East"},
-	foreign: map[string][]string{
-		"Asset": {"Make", "Model", "Serial"},
-		"Mount": {"Mount"},
+	foreign: map[string]map[string]string{
+		"Asset": {"Make": "Make", "Model": "Model", "Serial": "Serial"},
+		"Mount": {"Mount": "Mount"},
 	},
+	nullable: []string{"Notes"},
 	remap: map[string]string{
 		"Start Date": "Start",
 		"End Date":   "End",
diff --git a/meta/channel.go b/meta/channel.go
index f46de8a2b..066c0c5b7 100644
--- a/meta/channel.go
+++ b/meta/channel.go
@@ -27,13 +27,12 @@ var channelHeaders Header = map[string]int{
 }
 
 var ChannelTable Table = Table{
-	name:    "Channel",
-	headers: channelHeaders,
-	primary: []string{"Make", "Model", "Number", "SamplingRate"},
-	native:  []string{"Number", "SamplingRate"},
-	foreign: map[string][]string{
-		"Network": {"Network"},
-	},
+	name:     "Channel",
+	headers:  channelHeaders,
+	primary:  []string{"Make", "Model", "Number", "SamplingRate"},
+	native:   []string{"Number", "SamplingRate"},
+	foreign:  map[string]map[string]string{},
+	nullable: []string{"Number", "Response"},
 }
 
 // Channel is used to describe a generic recording from a Datalogger.
diff --git a/meta/citation.go b/meta/citation.go
index a3751265d..ff96286bf 100644
--- a/meta/citation.go
+++ b/meta/citation.go
@@ -34,11 +34,12 @@ var citationHeaders Header = map[string]int{
 }
 
 var CitationTable Table = Table{
-	name:    "Citation",
-	headers: citationHeaders,
-	primary: []string{"Key"},
-	native:  []string{"Year"},
-	foreign: map[string][]string{},
+	name:     "Citation",
+	headers:  citationHeaders,
+	primary:  []string{"Key"},
+	native:   []string{"Year"},
+	foreign:  map[string]map[string]string{},
+	nullable: []string{"DOI", "Link", "Pages", "Published", "Retrieved", "Volume"},
 }
 
 type Citation struct {
diff --git a/meta/class.go b/meta/class.go
index 070540904..7d2d5c49f 100644
--- a/meta/class.go
+++ b/meta/class.go
@@ -38,13 +38,12 @@ var classHeaders Header = map[string]int{
 }
 
 var ClassTable Table = Table{
-	name:    "Class",
-	headers: classHeaders,
-	primary: []string{"Station"},
-	native:  []string{"Vs30", "Basement Depth"},
-	foreign: map[string][]string{
-		"Citations": {"Citation"},
-	},
+	name:     "Class",
+	headers:  classHeaders,
+	primary:  []string{"Station"},
+	native:   []string{"Vs30", "Basement Depth"},
+	foreign:  map[string]map[string]string{},
+	nullable: []string{"Citations", "Link", "Notes"},
 	remap: map[string]string{
 		"Site Class":     "SiteClass",
 		"Vs30 Quality":   "Vs30Quality",
diff --git a/meta/component.go b/meta/component.go
index 525b94df7..e640f5e24 100644
--- a/meta/component.go
+++ b/meta/component.go
@@ -36,13 +36,12 @@ var componentHeaders Header = map[string]int{
 }
 
 var ComponentTable Table = Table{
-	name:    "Component",
-	headers: componentHeaders,
-	primary: []string{"Make", "Model", "Number", "Source", "Subsource", "Sampling Rate"},
-	native:  []string{"Number", "Dip", "Azimuth", "Sampling Rate"},
-	foreign: map[string][]string{
-		"Asset": {"Make", "Model"},
-	},
+	name:     "Component",
+	headers:  componentHeaders,
+	primary:  []string{"Make", "Model", "Number", "Source", "Subsource", "Sampling Rate"},
+	native:   []string{"Number", "Dip", "Azimuth", "Sampling Rate"},
+	foreign:  map[string]map[string]string{},
+	nullable: []string{"Sampling Rate", "Source", "Type"},
 	remap: map[string]string{
 		"Sampling Rate": "SamplingRate",
 	},
diff --git a/meta/connection.go b/meta/connection.go
index d1930fe16..4f9f77248 100644
--- a/meta/connection.go
+++ b/meta/connection.go
@@ -31,9 +31,10 @@ var ConnectionTable Table = Table{
 	name:    "Connection",
 	headers: connectionHeaders,
 	primary: []string{"Station", "Location", "Place", "Number", "Start Date"},
-	foreign: map[string][]string{
-		"Site": {"Station", "Location"},
+	foreign: map[string]map[string]string{
+		"Site": {"Station": "Station", "Location": "Location"},
 	},
+	nullable: []string{"Role", "Number", "Location"},
 	remap: map[string]string{
 		"Start Date": "Start",
 		"End Date":   "End",
diff --git a/meta/constituent.go b/meta/constituent.go
index abff66ee1..012ca7162 100644
--- a/meta/constituent.go
+++ b/meta/constituent.go
@@ -33,8 +33,8 @@ var ConstituentTable Table = Table{
 	headers: constituentHeaders,
 	primary: []string{"Gauge", "Number", "Start Date"},
 	native:  []string{"Amplitude", "Lage"},
-	foreign: map[string][]string{
-		"Gauge": {"Gauge"},
+	foreign: map[string]map[string]string{
+		"Gauge": {"Gauge": "Gauge"},
 	},
 	remap: map[string]string{
 		"Start Date": "Start",
diff --git a/meta/dart.go b/meta/dart.go
index 3f2679e11..386b589ef 100644
--- a/meta/dart.go
+++ b/meta/dart.go
@@ -28,7 +28,7 @@ var DartTable Table = Table{
 	headers: dartHeaders,
 	primary: []string{"Station", "Start Date"},
 	native:  []string{},
-	foreign: map[string][]string{},
+	foreign: map[string]map[string]string{},
 	remap: map[string]string{
 		"WMO Identifier": "WmoIdentifier",
 		"Start Date":     "Start",
diff --git a/meta/datalogger.go b/meta/datalogger.go
index be0869aff..7c73498f2 100644
--- a/meta/datalogger.go
+++ b/meta/datalogger.go
@@ -32,10 +32,11 @@ var DeployedDataloggerTable Table = Table{
 	headers: deployedDataloggerHeaders,
 	primary: []string{"Make", "Model", "Serial", "Place", "Role", "Start Date"},
 	native:  []string{},
-	foreign: map[string][]string{
-		"Asset":      {"Make", "Model", "Serial"},
-		"Connection": {"Place", "Role"},
+	foreign: map[string]map[string]string{
+		"Asset":      {"Make": "Make", "Model": "Model", "Serial": "Serial"},
+		"Connection": {"Place": "Place", "Role": "Role"},
 	},
+	nullable: []string{"Role"},
 	remap: map[string]string{
 		"Start Date": "Start",
 		"End Date":   "End",
diff --git a/meta/doas.go b/meta/doas.go
index 2ff3ad6f9..723dcfd49 100644
--- a/meta/doas.go
+++ b/meta/doas.go
@@ -43,9 +43,9 @@ var InstalledDoasTable Table = Table{
 	headers: installedDoasHeaders,
 	primary: []string{"Make", "Model", "Serial", "Start Date"},
 	native:  []string{"Azimuth", "Dip", "Height", "North", "East"},
-	foreign: map[string][]string{
-		"Asset": {"Make", "Model", "Serial"},
-		"Mount": {"Mount"},
+	foreign: map[string]map[string]string{
+		"Asset": {"Make": "Make", "Model": "Model", "Serial": "Serial"},
+		"Mount": {"Mount": "Mount"},
 	},
 	remap: map[string]string{
 		"Start Date": "Start",
diff --git a/meta/feature.go b/meta/feature.go
index edac38030..feec1acfb 100644
--- a/meta/feature.go
+++ b/meta/feature.go
@@ -33,9 +33,10 @@ var FeatureTable Table = Table{
 	name:    "Feature",
 	headers: featureHeaders,
 	primary: []string{"Station", "Location", "Sublocation", "Property", "Description", "Aspect", "Start Date"},
-	foreign: map[string][]string{
-		"Site": {"Station", "Location"},
+	foreign: map[string]map[string]string{
+		"Site": {"Station": "Station", "Location": "Location"},
 	},
+	nullable: []string{"Aspect", "Description", "Location", "Sublocation"},
 	remap: map[string]string{
 		"Start Date": "Start",
 		"End Date":   "End",
diff --git a/meta/firmware.go b/meta/firmware.go
index 7ac76872e..99b104ede 100644
--- a/meta/firmware.go
+++ b/meta/firmware.go
@@ -39,9 +39,10 @@ var FirmwareHistoryTable Table = Table{
 	headers: firmwareHistoryHeaders,
 	primary: []string{"Make", "Model", "Serial", "Start Date"},
 	native:  []string{},
-	foreign: map[string][]string{
-		"Asset": {"Make", "Model", "Serial"},
+	foreign: map[string]map[string]string{
+		"Asset": {"Make": "Make", "Model": "Model", "Serial": "Serial"},
 	},
+	nullable: []string{"Notes"},
 	remap: map[string]string{
 		"Start Date": "Start",
 		"End Date":   "End",
diff --git a/meta/gain.go b/meta/gain.go
index 5d1eedd70..e1e467041 100644
--- a/meta/gain.go
+++ b/meta/gain.go
@@ -34,14 +34,12 @@ var gainHeaders Header = map[string]int{
 }
 
 var GainTable Table = Table{
-	name:    "Gain",
-	headers: gainHeaders,
-	primary: []string{"Station", "Location", "Sublocation", "Subsource", "Start Date"},
-	native:  []string{"Scale Factor", "Scale Bias", "Absolute Bias"},
-	foreign: map[string][]string{
-		"Site":    {"Station", "Location"},
-		"Feature": {"Station", "Location", "Sublocation"},
-	},
+	name:     "Gain",
+	headers:  gainHeaders,
+	primary:  []string{"Station", "Location", "Sublocation", "Subsource", "Start Date"},
+	native:   []string{"Scale Factor", "Scale Bias", "Absolute Bias"},
+	foreign:  map[string]map[string]string{},
+	nullable: []string{"Absolute Bias", "Scale Bias", "Scale Factor", "Sublocation", "Subsource"},
 	remap: map[string]string{
 		"Scale Factor":  "Factor",
 		"Scale Bias":    "Bias",
diff --git a/meta/gauge.go b/meta/gauge.go
index 72f0329b5..277089773 100644
--- a/meta/gauge.go
+++ b/meta/gauge.go
@@ -38,8 +38,8 @@ var GaugeTable Table = Table{
 	//TODO: the Analysis Latitude is a used to avoid an overlap clash on NZC
 	primary: []string{"Gauge", "Identification Number", "Analysis Latitude", "Start Date"},
 	native:  []string{"Analysis Time Zone", "Analysis Latitude", "Analysis Longitude"},
-	foreign: map[string][]string{
-		"Network": {"Network"},
+	foreign: map[string]map[string]string{
+		"Network": {"Network": "Network"},
 	},
 	remap: map[string]string{
 		"Gauge":                 "Code",
diff --git a/meta/mark.go b/meta/mark.go
index d7243b671..54ef06b81 100644
--- a/meta/mark.go
+++ b/meta/mark.go
@@ -39,8 +39,8 @@ var MarkTable Table = Table{
 	headers: markHeaders,
 	primary: []string{"Mark", "Start Date"},
 	native:  []string{"Latitude", "Longitude", "Elevation"},
-	foreign: map[string][]string{
-		"Network": {"Network"},
+	foreign: map[string]map[string]string{
+		"Network": {"Network": "Network"},
 	},
 	remap: map[string]string{
 		"Mark":       "Code",
diff --git a/meta/metsensor.go b/meta/metsensor.go
index d4f242d43..df65fa18e 100644
--- a/meta/metsensor.go
+++ b/meta/metsensor.go
@@ -47,10 +47,11 @@ var InstalledMetSensorTable Table = Table{
 	headers: installedMetSensorHeaders,
 	primary: []string{"Make", "Model", "Serial", "Start Date"},
 	native:  []string{"Latitude", "Longitude", "Elevation", "Humidity", "Pressure", "Temperature"},
-	foreign: map[string][]string{
-		"Asset": {"Make", "Model", "Serial"},
-		"Mark":  {"Mark"},
+	foreign: map[string]map[string]string{
+		"Asset": {"Make": "Make", "Model": "Model", "Serial": "Serial"},
+		"Mark":  {"Mark": "Mark"},
 	},
+	nullable: []string{"IMS Comment"},
 	remap: map[string]string{
 		"IMS Comment": "IMSComment",
 		"Start Date":  "Start",
diff --git a/meta/monument.go b/meta/monument.go
index 5438176f5..c2167ff13 100644
--- a/meta/monument.go
+++ b/meta/monument.go
@@ -41,9 +41,10 @@ var MonumentTable Table = Table{
 	headers: monumentHeaders,
 	primary: []string{"Mark"},
 	native:  []string{"Ground Relationship", "Foundation Depth"},
-	foreign: map[string][]string{
-		"Mark": {"Mark"},
+	foreign: map[string]map[string]string{
+		"Mark": {"Mark": "Mark"},
 	},
+	nullable: []string{"Domes Number", "Geology", "Bedrock"},
 	remap: map[string]string{
 		"Domes Number":        "DomesNumber",
 		"Mark Type":           "MarkType",
diff --git a/meta/mount.go b/meta/mount.go
index c6137ee52..83eb30bd8 100644
--- a/meta/mount.go
+++ b/meta/mount.go
@@ -39,8 +39,8 @@ var MountTable Table = Table{
 	headers: mountHeaders,
 	primary: []string{"Mount", "Start Date"},
 	native:  []string{"Latitude", "Longitude", "Elevation"},
-	foreign: map[string][]string{
-		"Network": {"Network"},
+	foreign: map[string]map[string]string{
+		"Network": {"Network": "Network"},
 	},
 	remap: map[string]string{
 		"Mount":      "Code",
diff --git a/meta/network.go b/meta/network.go
index 5e6378e8c..96ccc8eb8 100644
--- a/meta/network.go
+++ b/meta/network.go
@@ -26,7 +26,7 @@ var NetworkTable Table = Table{
 	headers: networkHeaders,
 	primary: []string{"Network"},
 	native:  []string{},
-	foreign: map[string][]string{},
+	foreign: map[string]map[string]string{},
 	remap: map[string]string{
 		"Network": "Code",
 	},
diff --git a/meta/placenames.go b/meta/placenames.go
index eb97625ab..c23107403 100644
--- a/meta/placenames.go
+++ b/meta/placenames.go
@@ -30,11 +30,11 @@ var placenameHeaders Header = map[string]int{
 }
 
 var PlacenameTable Table = Table{
-	name:    "Name",
+	name:    "Placename",
 	headers: placenameHeaders,
 	primary: []string{"Name"},
 	native:  []string{"Latitude", "Longitude", "Level"},
-	foreign: map[string][]string{},
+	foreign: map[string]map[string]string{},
 }
 
 // Placename is used to describe distances and azimuths to known places.
diff --git a/meta/point.go b/meta/point.go
index 8e1bc1c19..88b60c860 100644
--- a/meta/point.go
+++ b/meta/point.go
@@ -39,9 +39,10 @@ var PointTable Table = Table{
 	headers: pointHeaders,
 	primary: []string{"Sample", "Location", "Start Date"},
 	native:  []string{"Latitude", "Longitude", "Elevation", "Depth"},
-	foreign: map[string][]string{
-		"Sample": {"Sample"},
+	foreign: map[string]map[string]string{
+		"Sample": {"Code": "Sample"},
 	},
+	nullable: []string{"Depth"},
 	remap: map[string]string{
 		"Start Date": "Start",
 		"End Date":   "End",
diff --git a/meta/polarity.go b/meta/polarity.go
index c2e8fafdd..bd00fc50b 100644
--- a/meta/polarity.go
+++ b/meta/polarity.go
@@ -40,9 +40,10 @@ var PolarityTable Table = Table{
 	primary: []string{"Station", "Location", "Sublocation", "Subsource", "Start Date"},
 	//native:  []string{"Primary", "Reversed"},
 	native: []string{},
-	foreign: map[string][]string{
-		"Site": {"Station", "Location"},
+	foreign: map[string]map[string]string{
+		"Site": {"Station": "Station", "Location": "Location"},
 	},
+	nullable: []string{"Citation", "Method", "Sublocation", "Subsource"},
 	remap: map[string]string{
 		"Primary":    "IsPrimary",
 		"Reversed":   "IsReversed",
diff --git a/meta/preamp.go b/meta/preamp.go
index 620f08186..6e7915387 100644
--- a/meta/preamp.go
+++ b/meta/preamp.go
@@ -32,9 +32,10 @@ var PreampTable Table = Table{
 	headers: preampHeaders,
 	primary: []string{"Station", "Location", "Subsource", "Start Date"},
 	native:  []string{"Scale Factor"},
-	foreign: map[string][]string{
-		"Site": {"Station", "Location"},
+	foreign: map[string]map[string]string{
+		"Site": {"Station": "Station", "Location": "Location"},
 	},
+	nullable: []string{"Subsource"},
 	remap: map[string]string{
 		"Scale Factor": "ScaleFactor",
 		"Start Date":   "Start",
diff --git a/meta/radome.go b/meta/radome.go
index 53525fef1..81ed500b2 100644
--- a/meta/radome.go
+++ b/meta/radome.go
@@ -30,8 +30,8 @@ var InstalledRadomeTable Table = Table{
 	headers: installedRadomeHeaders,
 	primary: []string{"Make", "Model", "Serial", "Start Date"},
 	native:  []string{},
-	foreign: map[string][]string{
-		"Mark": {"Mark"},
+	foreign: map[string]map[string]string{
+		"Mark": {"Mark": "Mark"},
 	},
 	remap: map[string]string{
 		"Start Date": "Start",
diff --git a/meta/receiver.go b/meta/receiver.go
index 89acc9bf3..4aebc9db6 100644
--- a/meta/receiver.go
+++ b/meta/receiver.go
@@ -30,9 +30,9 @@ var DeployedReceiverTable Table = Table{
 	headers: deployedReceiverHeaders,
 	primary: []string{"Make", "Model", "Serial", "Start Date"},
 	native:  []string{},
-	foreign: map[string][]string{
-		"Asset": {"Make", "Model", "Serial"},
-		"Mark":  {"Mark"},
+	foreign: map[string]map[string]string{
+		"Asset": {"Make": "Make", "Model": "Model", "Serial": "Serial"},
+		"Mark":  {"Mark": "Mark"},
 	},
 	remap: map[string]string{
 		"Start Date": "Start",
diff --git a/meta/recorder.go b/meta/recorder.go
index f34d2f0a4..51bf87377 100644
--- a/meta/recorder.go
+++ b/meta/recorder.go
@@ -43,9 +43,10 @@ var InstalledRecorderTable Table = Table{
 	headers: installedRecorderHeaders,
 	primary: []string{"Make", "Sensor", "Datalogger", "Serial", "Start Date"},
 	native:  []string{"Azimuth", "Dip", "Depth"},
-	foreign: map[string][]string{
-		"Asset": {"Make", "Model", "Serial"},
+	foreign: map[string]map[string]string{
+		"Asset": {"Make": "Make", "Model": "Sensor", "Serial": "Serial"},
 	},
+	nullable: []string{"Method"},
 	remap: map[string]string{
 		"Start Date": "Start",
 		"End Date":   "End",
diff --git a/meta/sample.go b/meta/sample.go
index 7f3b7152c..26a02f5d7 100644
--- a/meta/sample.go
+++ b/meta/sample.go
@@ -39,9 +39,10 @@ var SampleTable Table = Table{
 	headers: sampleHeaders,
 	primary: []string{"Station", "Start Date"},
 	native:  []string{"Latitude", "Longitude", "Elevation", "Depth"},
-	foreign: map[string][]string{
-		"Network": {"Network"},
+	foreign: map[string]map[string]string{
+		"Network": {"Network": "Network"},
 	},
+	nullable: []string{"Depth"},
 	remap: map[string]string{
 		"Station":    "Code",
 		"Start Date": "Start",
diff --git a/meta/sensor.go b/meta/sensor.go
index 9c79de800..35367e622 100644
--- a/meta/sensor.go
+++ b/meta/sensor.go
@@ -49,10 +49,11 @@ var InstalledSensorTable Table = Table{
 	headers: installedSensorHeaders,
 	primary: []string{"Make", "Model", "Serial", "Station", "Location", "Start Date"},
 	native:  []string{"Azimuth", "Dip", "Depth", "North", "East", "Scale Factor", "Scale Bias"},
-	foreign: map[string][]string{
-		"Asset": {"Make", "Model", "Serial"},
-		"Site":  {"Station", "Location"},
+	foreign: map[string]map[string]string{
+		"Asset": {"Make": "Make", "Model": "Model", "Serial": "Serial"},
+		"Site":  {"Station": "Station", "Location": "Location"},
 	},
+	nullable: []string{"Location", "Method"},
 	remap: map[string]string{
 		"Scale Factor": "Factor",
 		"Scale Bias":   "Bias",
diff --git a/meta/session.go b/meta/session.go
index 4bcb47dec..045708fa4 100644
--- a/meta/session.go
+++ b/meta/session.go
@@ -41,8 +41,8 @@ var SessionTable Table = Table{
 	headers: sessionHeaders,
 	primary: []string{"Mark", "Interval", "Start Date"},
 	native:  []string{"Elevation Mask"},
-	foreign: map[string][]string{
-		"Mark": {"Mark"},
+	foreign: map[string]map[string]string{
+		"Mark": {"Mark": "Mark"},
 	},
 	remap: map[string]string{
 		"Satellite System": "SatelliteSystem",
diff --git a/meta/site.go b/meta/site.go
index 42d86d8d9..6220e642e 100644
--- a/meta/site.go
+++ b/meta/site.go
@@ -39,9 +39,10 @@ var SiteTable Table = Table{
 	headers: siteHeaders,
 	primary: []string{"Station", "Location", "Start Date"},
 	native:  []string{"Latitude", "Longitude", "Elevation", "Depth"},
-	foreign: map[string][]string{
-		"Station": {"Station"},
+	foreign: map[string]map[string]string{
+		"Station": {"Station": "Station"},
 	},
+	nullable: []string{"Depth", "Location"}, //TODO: the Location shouldn't be empty
 	remap: map[string]string{
 		"Start Date": "Start",
 		"End Date":   "End",
diff --git a/meta/station.go b/meta/station.go
index edf0c26d7..f094d2601 100644
--- a/meta/station.go
+++ b/meta/station.go
@@ -45,9 +45,10 @@ var StationTable = Table{
 	headers: stationHeaders,
 	primary: []string{"Station", "Start Date"},
 	native:  []string{"Latitude", "Longitude", "Elevation", "Depth"},
-	foreign: map[string][]string{
-		"Network": {"Network"},
+	foreign: map[string]map[string]string{
+		"Network": {"Network": "Network"},
 	},
+	nullable: []string{"Depth"},
 	remap: map[string]string{
 		"Station":    "Code",
 		"Start Date": "Start",
diff --git a/meta/streams.go b/meta/streams.go
index 6c0320331..1cc6e6c57 100644
--- a/meta/streams.go
+++ b/meta/streams.go
@@ -39,9 +39,10 @@ var StreamTable Table = Table{
 	headers: streamHeaders,
 	primary: []string{"Station", "Location", "Source", "Sampling Rate", "Start Date"},
 	native:  []string{"Sampling Rate"},
-	foreign: map[string][]string{
-		"Site": {"Station", "Location"},
+	foreign: map[string]map[string]string{
+		"Site": {"Station": "Station", "Location": "Location"},
 	},
+	nullable: []string{"Band", "Source"},
 	remap: map[string]string{
 		"Sampling Rate": "SamplingRate",
 		"Start Date":    "Start",
diff --git a/meta/table.go b/meta/table.go
index 7db93b19c..3414bcec2 100644
--- a/meta/table.go
+++ b/meta/table.go
@@ -6,15 +6,17 @@ import (
 
 // Table holds internal settings suitable for automatic code generation.
 type Table struct {
-	name    string
-	headers Header
-	primary []string
-	native  []string
-	foreign map[string][]string
-	remap   map[string]string
-	ignore  bool
-	start   string
-	end     string
+	name     string
+	headers  Header
+	primary  []string
+	native   []string
+	foreign  map[string]map[string]string
+	nullable []string
+	defaults map[string]string
+	remap    map[string]string
+	ignore   bool
+	start    string
+	end      string
 }
 
 // Name returns the table name.
@@ -77,6 +79,28 @@ func (t Table) IsNative(col int) bool {
 	return false
 }
 
+// IsNullable returns whether the column can be set to NULL.
+func (t Table) IsNullable(col int) bool {
+	for _, s := range t.nullable {
+		if n, ok := t.headers[s]; !ok || n != col {
+			continue
+		}
+		return true
+	}
+	return false
+}
+
+// HasDefault returns whether the column has a default value.
+func (t Table) HasDefault(col int) (string, bool) {
+	for s, v := range t.defaults {
+		if n, ok := t.headers[s]; !ok || n != col {
+			continue
+		}
+		return v, true
+	}
+	return "", false
+}
+
 // IsDateTime returns whether the column is a date and may need extra formatting.
 func (t Table) IsDateTime(col int) bool {
 	for _, s := range []string{t.start, t.end} {
diff --git a/meta/telemetry.go b/meta/telemetry.go
index 885318d0d..36b0c885e 100644
--- a/meta/telemetry.go
+++ b/meta/telemetry.go
@@ -30,8 +30,11 @@ var TelemetryTable Table = Table{
 	headers: telemetryHeaders,
 	primary: []string{"Station", "Location", "Start Date"},
 	native:  []string{"Scale Factor"},
-	foreign: map[string][]string{
-		"Site": {"Station", "Location"},
+	foreign: map[string]map[string]string{
+		"Site": {"Station": "Station", "Location": "Location"},
+	},
+	defaults: map[string]string{
+		"Scale Factor": "1.0",
 	},
 	remap: map[string]string{
 		"Scale Factor": "ScaleFactor",
diff --git a/meta/timing.go b/meta/timing.go
index 07550c2f9..56fbbf3f2 100644
--- a/meta/timing.go
+++ b/meta/timing.go
@@ -28,8 +28,8 @@ var TimingTable Table = Table{
 	headers: timingHeaders,
 	primary: []string{"Station", "Location", "Start Date"},
 	native:  []string{},
-	foreign: map[string][]string{
-		"Site": {"Station", "Location"},
+	foreign: map[string]map[string]string{
+		"Site": {"Station": "Station", "Location": "Location"},
 	},
 	remap: map[string]string{
 		"Start Date": "Start",
diff --git a/meta/view.go b/meta/view.go
index 05ea3afef..adb9f957a 100644
--- a/meta/view.go
+++ b/meta/view.go
@@ -37,9 +37,10 @@ var ViewTable Table = Table{
 	headers: viewHeaders,
 	primary: []string{"Mount", "View", "Start Date"},
 	native:  []string{"Azimuth", "Dip"},
-	foreign: map[string][]string{
-		"Mount": {"Mount"},
+	foreign: map[string]map[string]string{
+		"Mount": {"Mount": "Mount"},
 	},
+	nullable: []string{"Label", "Method"},
 	remap: map[string]string{
 		"Start Date": "Start",
 		"End Date":   "End",
diff --git a/meta/visibility.go b/meta/visibility.go
index c84244609..24e7e0e6d 100644
--- a/meta/visibility.go
+++ b/meta/visibility.go
@@ -27,8 +27,8 @@ var VisibilityTable Table = Table{
 	//TODO: needs a column for describing feature
 	primary: []string{"Mark", "Start Date"},
 	native:  []string{},
-	foreign: map[string][]string{
-		"Mark": {"Mark"},
+	foreign: map[string]map[string]string{
+		"Mark": {"Mark": "Mark"},
 	},
 	remap: map[string]string{
 		"Sky Visibility": "SkyVisibility",