var (

	// SpanKind hints at relationship between spans, e.g. client/server
	SpanKind = spanKindTagName("span.kind")

	// SpanKindRPCClient marks a span representing the client-side of an RPC
	// or other remote call
	SpanKindRPCClientEnum = SpanKindEnum("client")
	SpanKindRPCClient     = opentracing.Tag{Key: string(SpanKind), Value: SpanKindRPCClientEnum}

	// SpanKindRPCServer marks a span representing the server-side of an RPC
	// or other remote call
	SpanKindRPCServerEnum = SpanKindEnum("server")
	SpanKindRPCServer     = opentracing.Tag{Key: string(SpanKind), Value: SpanKindRPCServerEnum}

	// SpanKindProducer marks a span representing the producer-side of a
	// message bus
	SpanKindProducerEnum = SpanKindEnum("producer")
	SpanKindProducer     = opentracing.Tag{Key: string(SpanKind), Value: SpanKindProducerEnum}

	// SpanKindConsumer marks a span representing the consumer-side of a
	// message bus
	SpanKindConsumerEnum = SpanKindEnum("consumer")
	SpanKindConsumer     = opentracing.Tag{Key: string(SpanKind), Value: SpanKindConsumerEnum}

	// Component is a low-cardinality identifier of the module, library,
	// or package that is generating a span.
	Component = StringTagName("component")

	// SamplingPriority determines the priority of sampling this Span.
	SamplingPriority = Uint16TagName("sampling.priority")

	// PeerService records the service name of the peer.
	PeerService = StringTagName("peer.service")

	// PeerAddress records the address name of the peer. This may be a "ip:port",
	// a bare "hostname", a FQDN or even a database DSN substring
	// like "mysql://username@127.0.0.1:3306/dbname"
	PeerAddress = StringTagName("peer.address")

	// PeerHostname records the host name of the peer
	PeerHostname = StringTagName("peer.hostname")

	// PeerHostIPv4 records IP v4 host address of the peer
	PeerHostIPv4 = IPv4TagName("peer.ipv4")

	// PeerHostIPv6 records IP v6 host address of the peer
	PeerHostIPv6 = StringTagName("peer.ipv6")

	// PeerPort records port number of the peer
	PeerPort = Uint16TagName("peer.port")

	// HTTPUrl should be the URL of the request being handled in this segment
	// of the trace, in standard URI format. The protocol is optional.
	HTTPUrl = StringTagName("http.url")

	// HTTPMethod is the HTTP method of the request, and is case-insensitive.
	HTTPMethod = StringTagName("http.method")

	// HTTPStatusCode is the numeric HTTP status code (200, 404, etc) of the
	// HTTP response.
	HTTPStatusCode = Uint16TagName("http.status_code")

	// DBInstance is database instance name.
	DBInstance = StringTagName("db.instance")

	// DBStatement is a database statement for the given database type.
	// It can be a query or a prepared statement (i.e., before substitution).
	DBStatement = StringTagName("db.statement")

	// DBType is a database type. For any SQL database, "sql".
	// For others, the lower-case database category, e.g. "redis"
	DBType = StringTagName("db.type")

	// DBUser is a username for accessing database.
	DBUser = StringTagName("db.user")

	// MessageBusDestination is an address at which messages can be exchanged
	MessageBusDestination = StringTagName("message_bus.destination")

	// Error indicates that operation represented by the span resulted in an error.
	Error = BoolTagName("error")
)

type BoolTagName string

type IPv4TagName string

type SpanKindEnum string

type StringTagName string

type Uint16TagName string

type Uint32TagName string