model {
  // Elements, top-levels are global, can be referenced anywhere in the project
  IDENTIFIER = KIND                   // without title, without body (title defaults to ID)
  IDENTIFIER = KIND "title"           // with title, without body
  KIND IDENTIFIER "title"             // if preferred by user to have kind before OD  
  IDENTIFIER = KIND {
    TAGS                              // optional, but must come first if present, before any properties
    PROPERTIES                        // optional, but must come before nested elements and relationships

    // order of nested elements vs relationships doesn't matter
    // Nested elements, can be referenced in this file by id, but from other files only using FQN, i.e. parentid.childid
    IDENTIFIER = KIND "Child Title" {
       // Same as above, no limit to nesting levels
    }
    KIND IDENTIFIER "Child Title" // if preferred by user to have kind before name

    // Explicit Relationship, SOURCE and TARGET must be resolvable within the current scope
    SOURCE -> TARGET
    // Implicit Relationship (current element is SOURCE)
    -> TARGET "Relationship title"
    -> TARGET "Relationship title" {
      TAGS                            // optional, but must come first if present, before any properties
      PROPERTIES                      // optional
    }
    // Relationship with kind
    -[REL_KIND]-> TARGET "Relationship title" 
    .REL_KIND -> TARGET "Relationship title"   // Alternative syntax for relationship with kind
    // "it" and "this" refer to the current element
    SOURCE -> it     // relationship to current element
    this -> TARGET   // relationship from current element
  }

  // Relationships on top level MUST have SOURCE
  SOURCE -> TARGET "Relationship title"    //without body
  SOURCE -> TARGET "Relationship title" {
    TAGS                                   // optional, but must come first if present, before any properties
    PROPERTIES                             // optional
  }
  SOURCE -[REL_KIND]-> TARGET
  SOURCE .REL_KIND TARGET

  // Extend existing element by FQN, e.g. from another file
  extend FQN { 
    TAGS                   // additional tags to apply to this element
    PROPERTIES             // additional properties to merge into this element, allowed `metadata` and `link` only

    NESTED_ELEMENTS | RELATIONSHIPS
  }
  // Extend existing relationship (must match existing relationship identity)
  // SOURCE and TARGET are always required. If multiple relationships exist between the
  // same endpoints, include kind and/or title to disambiguate the exact relationship.
  extend SOURCE -> TARGET  {
    TAGS                   // additional tags to apply to this relationship
    PROPERTIES             // additional properties to merge into this relationship, allowed `metadata` and `link` only
  }
  extend SOURCE -[REL_KIND]-> TARGET "Relationship title" {
    TAGS                   // additional tags to apply to this relationship
    PROPERTIES             // additional properties to merge into this relationship, allowed `metadata` and `link` only
  }
}

model {
  customer = actor "Customer" { description "End user" }

  cloud = system "Cloud" {
    ui = container "Frontend" {
      style { 
        shape browser
      }
      dashboard = app "Dashboard" { technology "React" }
    }
    backend = container "Backend" {
      api = service "API" { 
        #critical

        -[sql]-> db "reads/writes"
      }
      db = database "DB" { icon tech:postgresql }
    }
    ui.dashboard -> backend.api "calls" { technology "HTTPS" }
  }

  customer -> cloud.ui.dashboard "browses" {
    navigateTo browse-flow
    metadata { protocol "HTTPS" }
  }
}