diff --git a/models/domain.go b/models/domain.go
index 097d1bc87..b79c88d37 100644
--- a/models/domain.go
+++ b/models/domain.go
@@ -10,10 +10,17 @@ import (
 )
 
 const (
-	DomainTag         = "dnscontrol_tag"         // A copy of DomainConfig.Tag
-	DomainUniqueName  = "dnscontrol_uniquename"  // A copy of DomainConfig.UniqueName
-	DomainNameRaw     = "dnscontrol_nameraw"     // A copy of DomainConfig.NameRaw
-	DomainNameUnicode = "dnscontrol_nameunicode" // A copy of DomainConfig.NameUnicode
+	// DomainTag is the key used to store a copy of DomainConfig.Tag in the Metadata map.
+	DomainTag = "dnscontrol_tag"
+
+	// DomainUniqueName is the key used to store a copy of DomainConfig.UniqueName in the Metadata map.
+	DomainUniqueName = "dnscontrol_uniquename"
+
+	// DomainNameRaw is the key used to store a copy of DomainConfig.NameRaw in the Metadata map.
+	DomainNameRaw = "dnscontrol_nameraw"
+
+	// DomainNameUnicode is the key used to store a copy of DomainConfig.NameUnicode in the Metadata map.
+	DomainNameUnicode = "dnscontrol_nameunicode"
 )
 
 // DomainConfig describes a DNS domain (technically a DNS zone).
diff --git a/models/record.go b/models/record.go
index a16d2babe..4305d6818 100644
--- a/models/record.go
+++ b/models/record.go
@@ -540,8 +540,20 @@ func (rc *RecordConfig) GetSVCBValue() []dns.SVCBKeyValue {
 	return nil
 }
 
-// IsModernType returns true if this RecordConfig uses the new "F" field to store its rdata.
-// Once all record types have been migrated to use "F", this function can be removed.
+// IsModernType returns true if this RecordConfig is implemented in the new
+// ("Modern") way (i.e. uses the RecordConfig .F field to store the rdata of the
+// record).
+//
+// Since this check if .F != nil, it must be used only after the RecordConfig
+// has been populated. Otherwise, use rtypecontrol.IsModernType(recordTypeName),
+// which takes the type name as input.
+//
+// NOTE: Do not confuse this with rtypeinfo.IsModernType() which provides
+// similar functionality.  The difference is that this function is used to have
+// a RecordConfig reveal if it uses a modern type.  rtypeinfo.IsModernType()
+// takes the rtype name as a string argument.
+//
+// FUTURE(tlim): Once all record types have been migrated to use ".F", this function can be removed.
 func (rc *RecordConfig) IsModernType() bool {
 	return rc.F != nil
 }
diff --git a/models/t_loc.go b/models/t_loc.go
index 9ba1f8360..ddd8c19a4 100644
--- a/models/t_loc.go
+++ b/models/t_loc.go
@@ -200,6 +200,7 @@ func getENotationInt(x float32) (uint8, error) {
 	return packedValue, nil
 }
 
+// ReverseLatitude takes the packed latitude and returns the hemisphere, degrees, minutes, and seconds.
 func ReverseLatitude(lat uint32) (string, uint8, uint8, float64) {
 	var hemisphere string
 	if lat >= dns.LOC_EQUATOR {
@@ -218,6 +219,7 @@ func ReverseLatitude(lat uint32) (string, uint8, uint8, float64) {
 	return hemisphere, degrees, minutes, seconds
 }
 
+// ReverseLongitude takes the packed longitude and returns the hemisphere, degrees, minutes, and seconds.
 func ReverseLongitude(lon uint32) (string, uint8, uint8, float64) {
 	var hemisphere string
 	if lon >= dns.LOC_PRIMEMERIDIAN {
@@ -236,6 +238,7 @@ func ReverseLongitude(lon uint32) (string, uint8, uint8, float64) {
 	return hemisphere, degrees, minutes, seconds
 }
 
+// ReverseAltitude takes the packed altitude and returns the altitude in meters.
 func ReverseAltitude(packedAltitude uint32) float64 {
 	return float64(packedAltitude)/100 - 100000
 }
diff --git a/pkg/diff2/handsoff_test.go b/pkg/diff2/handsoff_test.go
index b0345d1f7..8136cd24d 100644
--- a/pkg/diff2/handsoff_test.go
+++ b/pkg/diff2/handsoff_test.go
@@ -280,8 +280,8 @@ func Test_ignore_external_dns(t *testing.T) {
 	// Check that external-dns records are in the result (so they won't be deleted)
 	foundMyappA := false
 	foundMyappTXT := false
-	foundApiCNAME := false
-	foundApiTXT := false
+	foundAPICNAME := false
+	foundAPITXT := false
 	foundStatic := false
 
 	for _, rec := range result {
@@ -291,9 +291,9 @@ func Test_ignore_external_dns(t *testing.T) {
 		case rec.GetLabel() == "a-myapp" && rec.Type == "TXT":
 			foundMyappTXT = true
 		case rec.GetLabel() == "api" && rec.Type == "CNAME":
-			foundApiCNAME = true
+			foundAPICNAME = true
 		case rec.GetLabel() == "cname-api" && rec.Type == "TXT":
-			foundApiTXT = true
+			foundAPITXT = true
 		case rec.GetLabel() == "static" && rec.Type == "A":
 			foundStatic = true
 		}
@@ -305,10 +305,10 @@ func Test_ignore_external_dns(t *testing.T) {
 	if !foundMyappTXT {
 		t.Error("Expected a-myapp TXT record to be preserved")
 	}
-	if !foundApiCNAME {
+	if !foundAPICNAME {
 		t.Error("Expected api CNAME record to be preserved")
 	}
-	if !foundApiTXT {
+	if !foundAPITXT {
 		t.Error("Expected cname-api TXT record to be preserved")
 	}
 	if !foundStatic {
diff --git a/pkg/domaintags/idn.go b/pkg/domaintags/idn.go
index 28cbcfde5..1b91fbe9c 100644
--- a/pkg/domaintags/idn.go
+++ b/pkg/domaintags/idn.go
@@ -2,28 +2,28 @@ package domaintags
 
 import "golang.org/x/net/idna"
 
+// EfficientToASCII converts a domain name to its ASCII representation using IDNA, on error returns the original name, and avoids wasting memory when possible.
 func EfficientToASCII(name string) string {
 	nameIDN, err := idna.ToASCII(name)
 	if err != nil {
 		return name // Fallback to raw name on error.
-	} else {
-		// Avoid pointless duplication.
-		if nameIDN == name {
-			return name
-		}
+	}
+	// Avoid pointless duplication.
+	if nameIDN == name {
+		return name
 	}
 	return nameIDN
 }
 
+// EfficientToUnicode converts a domain name to its Unicode representation using IDNA, on error returns the original name, and avoids wasting memory when possible.
 func EfficientToUnicode(name string) string {
 	nameUnicode, err := idna.ToUnicode(name)
 	if err != nil {
 		return name // Fallback to raw name on error.
-	} else {
-		// Avoid pointless duplication.
-		if nameUnicode == name {
-			return name
-		}
+	}
+	// Avoid pointless duplication.
+	if nameUnicode == name {
+		return name
 	}
 	return nameUnicode
 }
diff --git a/pkg/domaintags/permitlist.go b/pkg/domaintags/permitlist.go
index b3a61fbc5..6ebe91031 100644
--- a/pkg/domaintags/permitlist.go
+++ b/pkg/domaintags/permitlist.go
@@ -4,6 +4,10 @@ import (
 	"strings"
 )
 
+// PermitList is a structure that holds a pre-compiled version of the --domains
+// commmand line argument.  "all" means all domains are permitted and the rest
+// of the list is ignored. Otherwise, the list contains each element stored in a
+// variety of ways useful to the matching algorithm.
 type PermitList struct {
 	// If the permit list is "all" or "".
 	all   bool
@@ -33,6 +37,7 @@ func CompilePermitList(s string) PermitList {
 	return sl
 }
 
+// Permitted returns whether a domain is permitted by the PermitList.
 func (pl *PermitList) Permitted(domToCheck string) bool {
 
 	// If the permit list is "all", everything is permitted.
diff --git a/pkg/rtype/rp.go b/pkg/rtype/rp.go
index 6001f5c07..c4b9b15f2 100644
--- a/pkg/rtype/rp.go
+++ b/pkg/rtype/rp.go
@@ -17,6 +17,7 @@ type RP struct {
 	dns.RP
 }
 
+// Name returns the DNS record type as a string.
 func (handle *RP) Name() string {
 	return "RP"
 }
@@ -46,6 +47,7 @@ func (handle *RP) FromStruct(dcn *domaintags.DomainNameVarieties, rec *models.Re
 	return nil
 }
 
+// CopyToLegacyFields populates the legacy fields of the RecordConfig using the fields in .F.
 func (handle *RP) CopyToLegacyFields(rec *models.RecordConfig) {
 	rp := rec.F.(*RP)
 	_ = rec.SetTarget(rp.Mbox + " " + rp.Txt)
diff --git a/pkg/rtypecontrol/import.go b/pkg/rtypecontrol/import.go
index 1f0a5c285..7d3d011f5 100644
--- a/pkg/rtypecontrol/import.go
+++ b/pkg/rtypecontrol/import.go
@@ -32,6 +32,9 @@ func ImportRawRecords(domains []*models.DomainConfig) error {
 	return nil
 }
 
+// NewRecordConfigFromRaw creates a new RecordConfig from the raw ([]any) args,
+// usually from the parsed dnsconfig.js file, but also useful when a provider
+// returns the fields of a record as individual values.
 func NewRecordConfigFromRaw(t string, ttl uint32, args []any, dcn *domaintags.DomainNameVarieties) (*models.RecordConfig, error) {
 	if _, ok := Func[t]; !ok {
 		return nil, fmt.Errorf("record type %q is not supported", t)
@@ -57,6 +60,9 @@ func NewRecordConfigFromRaw(t string, ttl uint32, args []any, dcn *domaintags.Do
 	return rec, nil
 }
 
+// NewRecordConfigFromString creates a new RecordConfig from a string in the
+// format usually used in a zonefile but typically also used by providers
+// returning the fields of a record as a string.
 func NewRecordConfigFromString(name string, ttl uint32, t string, s string, dcn *domaintags.DomainNameVarieties) (*models.RecordConfig, error) {
 	if _, ok := Func[t]; !ok {
 		return nil, fmt.Errorf("record type %q is not supported", t)
@@ -73,6 +79,9 @@ func NewRecordConfigFromString(name string, ttl uint32, t string, s string, dcn
 
 }
 
+// NewRecordConfigFromStruct creates a new RecordConfig from a struct, typically
+// a miekg/dns struct. It must be the exact struct type used by the FromStruct()
+// method of the rtype package.
 func NewRecordConfigFromStruct(name string, ttl uint32, t string, fields any, dcn *domaintags.DomainNameVarieties) (*models.RecordConfig, error) {
 	if _, ok := Func[t]; !ok {
 		return nil, fmt.Errorf("record type %q is not supported", t)
diff --git a/pkg/rtypecontrol/rtypecontrol.go b/pkg/rtypecontrol/rtypecontrol.go
index 549918e2a..82b547bcd 100644
--- a/pkg/rtypecontrol/rtypecontrol.go
+++ b/pkg/rtypecontrol/rtypecontrol.go
@@ -8,9 +8,7 @@ import (
 	"github.com/StackExchange/dnscontrol/v4/providers"
 )
 
-// backwards compatibility:
-//var validTypes = map[string]struct{}{}
-
+// RType is an interface that defines the methods required for a DNS record type.
 type RType interface {
 	// Returns the name of the rtype ("A", "MX", etc.)
 	Name() string
@@ -22,9 +20,13 @@ type RType interface {
 	CopyToLegacyFields(*models.RecordConfig)
 }
 
-// Fun is a map of registered rtypes.
+// Func is a map of registered rtypes.
 var Func map[string]RType = map[string]RType{}
 
+// Register registers a new RType (Record Type) implementation. It can be used
+// to register an RFC-defined type, a new custom type, or a "builder".
+//
+// It panics if the type is already registered, to prevent accidental overwrites.
 func Register(t RType) {
 	name := t.Name()
 	if _, ok := Func[name]; ok {
@@ -36,8 +38,3 @@ func Register(t RType) {
 	// For compatibility with legacy systems:
 	providers.RegisterCustomRecordType(name, "", "")
 }
-
-func IsModernType(name string) bool {
-	_, ok := Func[name]
-	return ok
-}
diff --git a/pkg/rtypeinfo/rtypeinfo.go b/pkg/rtypeinfo/rtypeinfo.go
index f447926a7..5fc30e1c8 100644
--- a/pkg/rtypeinfo/rtypeinfo.go
+++ b/pkg/rtypeinfo/rtypeinfo.go
@@ -2,6 +2,19 @@ package rtypeinfo
 
 import "github.com/StackExchange/dnscontrol/v4/pkg/rtypecontrol"
 
+// IsModernType returns true if the given record type is implemented in the new
+// ("Modern") way. (i.e. uses the RecordConfig .F field to store the record's
+// rdata).
+//
+// Note that this does not simply check if .F != nil, which makes this function
+// useful before the RecordConfig is fully populated.
+//
+// NOTE: Do not confuse this with RecordConfig.IsModernType() which provides
+// similar functionality.  The difference is that this function receives the
+// type as a string, while RecordConfig.IsModernType() is a method on
+// RecordConfig that reveals if that specific RecordConfig instance is modern.
+//
+// FUTURE(tlim): Once all record types have been migrated to use ".F", this function can be removed.
 func IsModernType(t string) bool {
 	_, ok := rtypecontrol.Func[t]
 	return ok
diff --git a/pkg/transform/transform.go b/pkg/transform/transform.go
index a4c41d97b..6d3fbedce 100644
--- a/pkg/transform/transform.go
+++ b/pkg/transform/transform.go
@@ -104,15 +104,15 @@ func IPToList(address net.IP, transforms []IPConversion) ([]net.IP, error) {
 		return nil, err
 	}
 	for _, conv := range transforms {
-		min_, err := ipToUint(conv.Low)
+		minIP, err := ipToUint(conv.Low)
 		if err != nil {
 			return nil, err
 		}
-		max_, err := ipToUint(conv.High)
+		maxIP, err := ipToUint(conv.High)
 		if err != nil {
 			return nil, err
 		}
-		if (thisIP >= min_) && (thisIP <= max_) {
+		if (thisIP >= minIP) && (thisIP <= maxIP) {
 			if len(conv.NewIPs) > 0 {
 				return conv.NewIPs, nil
 			}
@@ -122,7 +122,7 @@ func IPToList(address net.IP, transforms []IPConversion) ([]net.IP, error) {
 				if err != nil {
 					return nil, err
 				}
-				list = append(list, UintToIP(newbase+(thisIP-min_)))
+				list = append(list, UintToIP(newbase+(thisIP-minIP)))
 			}
 			return list, nil
 		}
diff --git a/pkg/zonecache/zonecache.go b/pkg/zonecache/zonecache.go
index 734f65bbe..b4adfa7c9 100644
--- a/pkg/zonecache/zonecache.go
+++ b/pkg/zonecache/zonecache.go
@@ -5,12 +5,15 @@ import (
 	"sync"
 )
 
+// New creates a new ZoneCache of the given Zone type.
 func New[Zone any](fetchAll func() (map[string]Zone, error)) ZoneCache[Zone] {
 	return ZoneCache[Zone]{fetchAll: fetchAll}
 }
 
+// ErrZoneNotFound is returned when a requested zone is not found (in the cache).
 var ErrZoneNotFound = errors.New("zone not found")
 
+// ZoneCache is a thread-safe cache for DNS zones at this provider.
 type ZoneCache[Zone any] struct {
 	mu       sync.Mutex
 	cached   bool
@@ -36,6 +39,7 @@ func (c *ZoneCache[Zone]) ensureCached() error {
 	return nil
 }
 
+// HasZone returns true if the zone with the given name exists (in the cache).
 func (c *ZoneCache[Zone]) HasZone(name string) (bool, error) {
 	c.mu.Lock()
 	defer c.mu.Unlock()
diff --git a/providers/adguardhome/api.go b/providers/adguardhome/api.go
index aa4cee7bf..65c3618dc 100644
--- a/providers/adguardhome/api.go
+++ b/providers/adguardhome/api.go
@@ -72,9 +72,8 @@ retry:
 
 	if resp.StatusCode == http.StatusOK {
 		return bodyString, nil
-	} else {
-		return nil, errors.New(string(bodyString))
 	}
+	return nil, errors.New(string(bodyString))
 }
 
 func (c *adguardHomeProvider) get(endpoint string) ([]byte, error) {
@@ -112,9 +111,8 @@ retry:
 
 	if resp.StatusCode == http.StatusOK {
 		return bodyString, nil
-	} else {
-		return nil, errors.New(string(bodyString))
 	}
+	return nil, errors.New(string(bodyString))
 }
 
 func (c *adguardHomeProvider) createRecord(r rewriteEntry) error {
diff --git a/providers/autodns/types.go b/providers/autodns/types.go
index f86131396..a26efe1b1 100644
--- a/providers/autodns/types.go
+++ b/providers/autodns/types.go
@@ -70,6 +70,7 @@ type Domain struct {
 	Zone        *Zone         `json:"zone,omitempty"`
 }
 
+// NameServer represents a nameserver in API calls.
 type NameServer struct {
 	// Host name of the nameserver written as a Fully-Qualified-Domain-Name (FQDN).
 	Name string `json:"name"`
@@ -85,6 +86,7 @@ type JSONResponseDataZone struct {
 	Data []*Zone `json:"data"`
 }
 
+// JSONResponseDataDomain represents the response to the DataDomain call.
 type JSONResponseDataDomain struct {
 	// The data for the response. The type of the objects are depending on the request and are also specified in the responseObject value of the response.
 	Data []*Domain `json:"data"`
diff --git a/providers/cloudflare/rtypes/cfsingleredirect/cfredirect.go b/providers/cloudflare/rtypes/cfsingleredirect/cfredirect.go
index 0ea8e29c7..00b9aab5d 100644
--- a/providers/cloudflare/rtypes/cfsingleredirect/cfredirect.go
+++ b/providers/cloudflare/rtypes/cfsingleredirect/cfredirect.go
@@ -13,6 +13,7 @@ func init() {
 	rtypecontrol.Register(&CfTempRedirect{})
 }
 
+// CfRedirect represents the CF_REDIRECT rtype, which is a builder that produces CLOUDFLAREAPI_SINGLE_REDIRECT.
 type CfRedirect struct{}
 
 // Name returns the text (all caps) name of the rtype.
@@ -20,18 +21,22 @@ func (handle *CfRedirect) Name() string {
 	return "CF_REDIRECT"
 }
 
+// FromArgs populates a RecordConfig from the raw ([]any) args.
 func (handle *CfRedirect) FromArgs(dcn *domaintags.DomainNameVarieties, rec *models.RecordConfig, args []any) error {
-	return FromArgsHelper(dcn, rec, args, 301)
+	return fromArgsHelper(dcn, rec, args, 301)
 }
 
+// FromStruct populates a RecordConfig from a struct, which will be stored in rec.F.
 func (handle *CfRedirect) FromStruct(dcn *domaintags.DomainNameVarieties, rec *models.RecordConfig, name string, fields any) error {
 	panic("CF_REDIRECT: FromStruct not implemented")
 }
 
+// CopyToLegacyFields copies data from rec.F to the legacy fields in rec.
 func (handle *CfRedirect) CopyToLegacyFields(rec *models.RecordConfig) {
 	// Nothing needs to be copied.  The CLOUDFLAREAPI_SINGLE_REDIRECT FromArgs copies everything needed.
 }
 
+// CfTempRedirect represents the CF_TEMP_REDIRECT rtype, which is a builder that produces CLOUDFLAREAPI_SINGLE_REDIRECT.
 type CfTempRedirect struct{}
 
 // Name returns the text (all caps) name of the rtype.
@@ -39,19 +44,22 @@ func (handle *CfTempRedirect) Name() string {
 	return "CF_TEMP_REDIRECT"
 }
 
+// FromArgs populates a RecordConfig from the raw ([]any) args.
 func (handle *CfTempRedirect) FromArgs(dcn *domaintags.DomainNameVarieties, rec *models.RecordConfig, args []any) error {
-	return FromArgsHelper(dcn, rec, args, 302)
+	return fromArgsHelper(dcn, rec, args, 302)
 }
 
+// FromStruct populates a RecordConfig from a struct, which will be stored in rec.F.
 func (handle *CfTempRedirect) FromStruct(dcn *domaintags.DomainNameVarieties, rec *models.RecordConfig, name string, fields any) error {
 	panic("CF_TEMP_REDIRECT: FromStruct not implemented")
 }
 
+// CopyToLegacyFields copies data from rec.F to the legacy fields in rec.
 func (handle *CfTempRedirect) CopyToLegacyFields(rec *models.RecordConfig) {
 	// Nothing needs to be copied.  The CLOUDFLAREAPI_SINGLE_REDIRECT FromArgs copies everything needed.
 }
 
-func FromArgsHelper(dcn *domaintags.DomainNameVarieties, rec *models.RecordConfig, args []any, code int) error {
+func fromArgsHelper(dcn *domaintags.DomainNameVarieties, rec *models.RecordConfig, args []any, code int) error {
 
 	// Pave the args to be the expected types.
 	if err := rtypecontrol.PaveArgs(args, "ss"); err != nil {
diff --git a/providers/cloudflare/rtypes/cfsingleredirect/cfsingleredirect.go b/providers/cloudflare/rtypes/cfsingleredirect/cfsingleredirect.go
index 1545668b3..a55b49c85 100644
--- a/providers/cloudflare/rtypes/cfsingleredirect/cfsingleredirect.go
+++ b/providers/cloudflare/rtypes/cfsingleredirect/cfsingleredirect.go
@@ -31,6 +31,7 @@ func (handle *SingleRedirectConfig) Name() string {
 	return "CLOUDFLAREAPI_SINGLE_REDIRECT"
 }
 
+// FromArgs populates a RecordConfig from the raw ([]any) args.
 func (handle *SingleRedirectConfig) FromArgs(dcn *domaintags.DomainNameVarieties, rec *models.RecordConfig, args []any) error {
 	// Pave the args to be the expected types.
 	if err := rtypecontrol.PaveArgs(args, "siss"); err != nil {
@@ -77,6 +78,7 @@ func (handle *SingleRedirectConfig) FromArgs(dcn *domaintags.DomainNameVarieties
 	return nil
 }
 
+// FromStruct populates a RecordConfig from a struct, which will be stored in rec.F.
 func (handle *SingleRedirectConfig) FromStruct(dcn *domaintags.DomainNameVarieties, rec *models.RecordConfig, name string, fields any) error {
 	panic("CLOUDFLAREAPI_SINGLE_REDIRECT: FromStruct not implemented")
 }
@@ -91,6 +93,7 @@ func targetFromRaw(name string, code uint16, when, then string) string {
 	)
 }
 
+// CopyToLegacyFields copies data from rec.F to the legacy fields in rec.
 func (handle *SingleRedirectConfig) CopyToLegacyFields(rec *models.RecordConfig) {
 	_ = rec.SetTarget(rec.F.(*SingleRedirectConfig).SRDisplay)
 }
diff --git a/providers/exoscale/exoscaleProvider.go b/providers/exoscale/exoscaleProvider.go
index 136e1fa5f..ec881ff65 100644
--- a/providers/exoscale/exoscaleProvider.go
+++ b/providers/exoscale/exoscaleProvider.go
@@ -219,11 +219,11 @@ func (c *exoscaleProvider) GetZoneRecordsCorrections(dc *models.DomainConfig, ex
 	}
 
 	for _, mod := range modify {
-		old_ := mod.Existing.Original.(*egoscale.DNSDomainRecord)
-		new_ := mod.Desired
+		oldRec := mod.Existing.Original.(*egoscale.DNSDomainRecord)
+		newRec := mod.Desired
 		corrections = append(corrections, &models.Correction{
 			Msg: mod.String(),
-			F:   c.updateRecordFunc(old_, new_, domainID),
+			F:   c.updateRecordFunc(oldRec, newRec, domainID),
 		})
 	}
 
diff --git a/providers/fortigate/fortigateProvider.go b/providers/fortigate/fortigateProvider.go
index af96562c9..206af9b30 100644
--- a/providers/fortigate/fortigateProvider.go
+++ b/providers/fortigate/fortigateProvider.go
@@ -45,8 +45,7 @@ type fortigateProvider struct {
 	client   *apiClient
 }
 
-// Constructor
-
+// NewFortiGate creates a new instance of the FortiGate DNS provider.
 func NewFortiGate(m map[string]string, _ json.RawMessage) (providers.DNSServiceProvider, error) {
 	host, vdom, apiKey := m["host"], m["vdom"], m["apiKey"]
 
diff --git a/providers/hexonet/records.go b/providers/hexonet/records.go
index 37b2c1b38..5b28afdf9 100644
--- a/providers/hexonet/records.go
+++ b/providers/hexonet/records.go
@@ -92,10 +92,10 @@ func (n *HXClient) GetZoneRecordsCorrections(dc *models.DomainConfig, actual mod
 	for _, chng := range mod {
 		changes = true
 		fmt.Fprintln(buf, chng)
-		old_ := chng.Existing.Original.(*HXRecord)
-		new_ := chng.Desired
-		params[fmt.Sprintf("DELRR%d", delrridx)] = n.deleteRecordString(old_)
-		newRecordString, err := n.createRecordString(new_, dc.Name)
+		oldRec := chng.Existing.Original.(*HXRecord)
+		newRec := chng.Desired
+		params[fmt.Sprintf("DELRR%d", delrridx)] = n.deleteRecordString(oldRec)
+		newRecordString, err := n.createRecordString(newRec, dc.Name)
 		if err != nil {
 			return corrections, 0, err
 		}
diff --git a/providers/namedotcom/records.go b/providers/namedotcom/records.go
index 755630e18..b918fbf31 100644
--- a/providers/namedotcom/records.go
+++ b/providers/namedotcom/records.go
@@ -56,14 +56,14 @@ func (n *namedotcomProvider) GetZoneRecordsCorrections(dc *models.DomainConfig,
 		corrections = append(corrections, c)
 	}
 	for _, chng := range mod {
-		old_ := chng.Existing.Original.(*namecom.Record)
-		new_ := chng.Desired
+		oldRec := chng.Existing.Original.(*namecom.Record)
+		newRec := chng.Desired
 		c := &models.Correction{Msg: chng.String(), F: func() error {
-			err := n.deleteRecord(old_.ID, dc.Name)
+			err := n.deleteRecord(oldRec.ID, dc.Name)
 			if err != nil {
 				return err
 			}
-			return n.createRecord(new_, dc.Name)
+			return n.createRecord(newRec, dc.Name)
 		}}
 		corrections = append(corrections, c)
 	}
diff --git a/providers/providers.go b/providers/providers.go
index b8b396b4f..b0639f477 100644
--- a/providers/providers.go
+++ b/providers/providers.go
@@ -74,8 +74,10 @@ func RegisterDomainServiceProviderType(name string, fns DspFuncs, pm ...Provider
 	unwrapProviderCapabilities(name, pm)
 }
 
+// ProviderMaintainers stores the GitHub usernames of maintainers for each provider.
 var ProviderMaintainers = map[string]string{}
 
+// RegisterMaintainer registers the GitHub username of the maintainer for a provider.
 func RegisterMaintainer(
 	providerName string,
 	gitHubUsername string,
diff --git a/providers/realtimeregister/api.go b/providers/realtimeregister/api.go
index 4b3805599..0640c7080 100644
--- a/providers/realtimeregister/api.go
+++ b/providers/realtimeregister/api.go
@@ -16,14 +16,17 @@ type realtimeregisterAPI struct {
 	ServiceType string
 }
 
+// Zones represents a collection of DNS zones in Realtime Register.
 type Zones struct {
 	Entities []Zone `json:"entities"`
 }
 
+// Domain represents a domain in Realtime Register.
 type Domain struct {
 	Nameservers []string `json:"ns"`
 }
 
+// Zone represents a DNS zone in Realtime Register.
 type Zone struct {
 	Name    string   `json:"name,omitempty"`
 	Service string   `json:"service,omitempty"`
@@ -32,6 +35,7 @@ type Zone struct {
 	Dnssec  bool     `json:"dnssec"`
 }
 
+// Record represents a DNS record in Realtime Register.
 type Record struct {
 	Name     string `json:"name"`
 	Type     string `json:"type"`
diff --git a/providers/sakuracloud/api.go b/providers/sakuracloud/api.go
index 57893a641..3f146113c 100644
--- a/providers/sakuracloud/api.go
+++ b/providers/sakuracloud/api.go
@@ -269,6 +269,7 @@ type sakuracloudAPI struct {
 	commonServiceItemMap map[string]*commonServiceItem
 }
 
+// NewSakuracloudAPI creates and returns a sakuracloudAPI instance.
 func NewSakuracloudAPI(accessToken, accessTokenSecret, endpoint string) (*sakuracloudAPI, error) {
 	baseURL, err := url.Parse(endpoint)
 	if err != nil {