General The CAD Layer Guidelines are organized as hierarchy. This arrangement accommodates expansion and addition 0f user-defined extensions to the layer list. Layer names are alphanumeric and use abbreviations that are easy to remember. This legibility is particularly important when CAD files are distributed among architects, consultants, and clients. Layer names consist of a Discipline Code- Major Group-Minor Group-Status Field. The format for the CAD Standard is as follows:
Architectural Layer Standards Discipline Code Discipline is the primary method of classification for layer names. The discipline code provides a path back to the originator of the data and provides a logical categorization of CAD information. The discipline code is intended primarily to identify the author of the graphic information. Thus, a structural column placed by an architect would be A-COLS rather than S-COLS. The existence of both sets of information can in fact indicate the need for coordination. The Discipline Code is a one or two- character field with the second character either a hyphen or a user-defined modifier. The discipline codes are listed below. A Architectural MMechanical CCivilPPlumbing EElectricalQEquipment FFire ProtectionRResource GGeneralSStructural HHazardous MaterialsTTelecommunications IInteriorsXOther LLandscapeZContractor/shop Drawings
Architectural Layer Standards Major Group The Major Group designation identifies the building system. This field must contain four characters. Although Major Groups are logically grouped with specific discipline codes, it is possible to combine Major Groups with any of the Discipline Codes. For example, a drawing might contain the following layers. A-Roof RoofA-Anno Annotation A-Beam Beam A-Chim Chimney A-Cols Columns A-Deck Floor Decks A-Detl Detail A-DoorDoors A-Elev Elevation A-FixtPlumbing Fixtures A-Fixt FixtureA-Fndn Foundation A-Furn Furniture A-Glaz Glass A-Hvac H.V.A.C A-Jois Joists A-LiteLighting FixturesA-Pkng Parking A-Sect Sections A-Site Site A-Slab SlabsA-Spcl Special A-Walk WalksA-Wall Walls
Architectural Layer Standards Minor Group This is an optional, four-character field for further differentiation of Major Groups. For example, A-WALL-PART indicates architecture, new, wall partial height. The following modifiers are defined for use in the Minor Group field. Appl Appliances Bnch Benchmarks Cars Graphic Illustration of Cars Cols Columns Dims Dimensions Elev Elevations, Elevation text, 3D, etc. Esmt Easements, Row, and Setback LinesFenc Fencing Fixt Fixtures Grnd Bushes, Ground Covers and Vines Iden Identification Legn Schedule, Legend, Misc MiscellaneousNote Notes PattHatch Pattern NumberPeop People Pfix Plumbing Fixtures Roof Roof Site SiteStep Steps Strs Stairs, Treads, Escalators, and ladders Symb Symbols Tele Telephone Text Legends and Schedules Text Ther ThermostatsTptn Toilet Partitions Ttbl Title Blocks
Architectural Layer Standards Annotation Annotation comprises text, dimensions, sheet borders. Detail references, and other elements on CAD drawings that don’t represent physical aspects of a building. The major group "ANNO" designates annotation. Types of annotation are as follows: A-Anno-Dims Dimensions A-Anno-Keyn Keynotes A-Anno-LegnLegends And Schedules A-Anno-NoteNotes A-Anno-Nplt Construction Lines, Non-Plotting Information A-Anno-Redl Redline A-Anno-Revs Revisions A-Anno-Symb Symbols A-Anno-Text Text A-Anno-Ttlb Border And Title Block Annotation can be placed in both paper and model space (Model files/Sheet files). Dimensions, symbols, and keynotes would typically be placed in model space. Legends, schedules, borders, and title blocks would typically be placed in paper space. The same layer names would be used in both cases. A special case exists when a single model file (x-reference) is referenced by two or more "sets" of annotation. A model file containing both floor plan and ceiling plan information many need different layers for ceiling plan dimensions and floor plan dimensions. In this case, users should modify the Minor Group to indicate the intended view. For example, A-ANNO-DMFP for floor plan dimensions and A-ANNO-DMCP for ceiling plan dimensions.
Architectural Layer Standards User-Definable Fields The Minor Group field can be defined by the user, allowing additional layers to be added to accommodate special project requirements. This should only be done if a desired layer does not apply to a project. Some examples of layers using a user-defined Minor Group field are as follows. A-Door-Metl Metal Doors A-Wall-Strc Walls To Structure A-Furn-Pnl1 Furniture Panels From Manufacturer 1 A-Furn-Pnl2 Furniture Panels From Manufacturer 2 In contrast to the first edition of "CAD Layer Guidelines", this edition does not incorporate a fourth level of hierarchy for the use-defined layers. In other words, users should use a layer such as A-DOOR-MIDN instead of A-DOOR-METL-IDEN. Because the Minor Group can accept any user-defined code, the revised format accommodates flexibility while avoiding long, cumbersome layer names.
Architectural Layer Standards Layers for Elevations, Details, Sections, and Vertical Drawings Special Groups of layers within each discipline are defined for elevations, sections, details, and three-dimensional views. Defined layer groups are as follows. *-Elev Elevations *-Elev-Iden Component Identification Numbers *-Elev-Otln Building Outlines *-Elev-Patt Textures And Hatch Patterns With Different Pens *-Sect Sections *-Sect-Iden Component Identification Numbers *-Sect-Mbnd Material Beyond Section Cut *-Sect-Mcut Material Cut By Section *-Sect-Patt Textures And Hatch Patterns With Different Pens *-Detl Details *-Detl-Iden Component Identification Numbers *-Detl-Mbnd Material Beyond Section Cut *-Detl-Mcut Material Cut By Section *-Detl-Patt Textures And Hatch Patterns With Different Pens The Minor Group "*-ELEV" can be added to any Major Group layer (A-WALL, A-DOOR, Etc.) to identify information only seen in 3D views. This facilitates integrating three-dimensional CAD models with two-dimensional plans as shown below. A-Wall Walls In Plan View A-Wall-Elev Wall Surfaces In 3D Views