L0 = <http://www.simantics.org/Layer0-1.1>
STR = <http://www.simantics.org/Structural-1.2>
DIA = <http://www.simantics.org/Diagram-2.2>

//// CONNECTION BRANCHING / ROUTING

DIA.HasInverseAttachment <R L0.IsRelatedTo : L0.FunctionalRelation
    @L0.symmetric
    L0.HasDescription "Identifies the inversely directed connector attachment relation of a DIA.HasConnector relation. For example, DIA.HasPlainConnector is the inverse attachment relation of DIA.HasArrowConnector."

DIA.HasConnector <R STR.IsConnectedTo <R L0.IsComposedOf
    L0.InverseOf DIA.IsConnectorOf
    L0.HasDomain DIA.Connection
    --> DIA.Connector
DIA.HasTailConnector <R DIA.HasConnector
    L0.HasDescription "Identifies, where applicable, the beginning of the connection"
    L0.InverseOf DIA.IsTailConnectorOf
DIA.HasHeadConnector <R DIA.HasConnector
    L0.HasDescription "Identifies, where applicable, the end of the connection"
    L0.InverseOf DIA.IsHeadConnectorOf
    DIA.HasInverseAttachment DIA.HasTailConnector
DIA.HasPlainConnector <R DIA.HasTailConnector
    L0.HasDescription "Identifies a connection end where no arrowhead is drawn."
    L0.InverseOf DIA.IsPlainConnectorOf
DIA.HasArrowConnector <R DIA.HasHeadConnector
    L0.HasDescription "Identifies a connection end with an arrow."
    L0.InverseOf DIA.IsArrowConnectorOf
    DIA.HasInverseAttachment DIA.HasPlainConnector
DIA.HasBranchPoint <R DIA.HasInteriorRouteNode
    L0.InverseOf DIA.IsBranchPointOf
    L0.HasDomain DIA.Connection
    --> DIA.BranchPoint
DIA.AreConnected <R L0.IsWeaklyRelatedTo
    @L0.symmetric
    // TODO L0.HasDomain DIA.Connector or DIA.BranchPoint
    // TODO --> DIA.Connector or DIA.BranchPoint

DIA.Connector <T STR.Connection : L0.Type
// HN: removed, cannot be valid requirements
    @L0.property DIA.AreConnected
    @L0.property STR.Connects

DIA.Connection <T DIA.Element : L0.Type
    >-- DIA.HasTransform
    @L0.property DIA.HasPlainConnector
    @L0.property DIA.HasArrowConnector
    @L0.property DIA.HasBranchPoint
    @L0.property STR.HasConnectionType
    @L0.property DIA.Routing

DIA.BranchPoint <T DIA.InteriorRouteNode
    @L0.property DIA.Horizontal
    @L0.property DIA.Vertical
    @L0.property DIA.AreConnected

DIA.Horizontal
    @L0.defTag 
DIA.Vertical
    @L0.defTag

DIA.RoutingRelation : L0.Relation
DIA.Routing : DIA.RoutingRelation
    @L0.tag L0.Abstract
    @L0.defTag
    L0.HasDescription "A relation meant to be inherited to create specific tags describing how a connection should be routed. The relation itself should be made adaptable to a routing strategy class org.simantics.g2d.routing.IRouter2. A connection can only have 0 to 1 Routing tags."
DIA.LinearRouting <R DIA.Routing
    @L0.symmetric
    L0.HasLabel "Straight"
    L0.HasDescription "Connection line segments will be routed with straight lines between terminals, route points and branch points."
DIA.RightAngledRouting <R DIA.Routing
    @L0.symmetric
    L0.HasLabel "Right-angled"
    L0.HasDescription "Connection line segments will be routed with x/y axis-aligned right-angled lines between so that the connection will is guaranteed to pass through each route and branch point."

DIA.HasDefaultRouting <R L0.IsRelatedTo
    L0.HasDomain STR.ConnectionType
    --> DIA.RoutingRelation

// NOTE: attach the diagram ontology default attachment relation to default structural modelling rules.
STR.DefaultModelingRules
    STR.HasAttachmentRelation DIA.HasPlainConnector