Last reviewed 16 Sept 2026 · 8 min read
Object properties
| Property | Description |
|---|---|
| Colour | AutoCAD Color Index (ACI) 1–255 (1 red, 2 yellow, 3 green, 4 cyan, 5 blue, 6 magenta, 7 white/black), true colour or colour books; often used to control plot lineweights via colour-dependent plot styles |
| Linetype | Continuous, HIDDEN (dashed), CENTER (chain), DASHDOT, PHANTOM, etc. — loaded from acad.lin/acadiso.lin via LINETYPE |
| Linetype scale | LTSCALE — global scale for dash spacing; CELTSCALE — for new objects; object linetype scale in Properties; PSLTSCALE — scales linetypes by viewport scale in paper space; MSLTSCALE — scales by annotation scale in model space |
| Lineweight | Thickness of printed lines (e.g. 0.13–2.11 mm); display toggled with LWT |
| Transparency | 0–90% |
| Plot style | Named plot styles (when used) |
ByLayer and ByBlock
- ByLayer — object takes the property of its layer (recommended practice — control properties centrally through layers).
- ByBlock — objects inside a block take the properties assigned to the block reference when inserted.
- Directly assigned properties (overrides) make management harder.
Layers
Layers are like transparent overlays used to organise drawing content by type (walls, doors, dimensions, text, hatches, furniture, electrical, plumbing, structural).
Benefits
- Control visibility of groups of objects.
- Assign colour, linetype, lineweight and plot settings consistently.
- Prevent accidental editing (lock).
- Produce different drawings from the same file (e.g. architectural vs electrical plans) by switching layers.
- Support CAD standards and collaboration.
Layer Properties Manager (LAYER / LA)
| Setting | Effect |
|---|---|
| Current layer | New objects are drawn on it |
| On / Off | Off layers are invisible and not plotted, but still regenerated and can be selected with ALL (in some operations) |
| Freeze / Thaw | Frozen layers are invisible, not plotted, not regenerated (improves performance) and not selectable; the current layer cannot be frozen |
| Lock / Unlock | Locked layer objects are visible and snappable but cannot be edited; shown faded |
| Plot / No plot | Controls plotting while remaining visible (e.g. construction lines, viewport borders) |
| VP Freeze | Freeze in a specific layout viewport only |
| Colour, Linetype, Lineweight, Transparency, Plot style | Layer-level properties |
| New VP Freeze | Frozen in newly created viewports |
Special layers
- Layer 0 — default layer; cannot be deleted or renamed; objects on layer 0 inside blocks take the properties of the layer on which the block is inserted (useful for creating blocks).
- Defpoints — created automatically with dimensions; objects on it do not plot.
- Layers containing objects, the current layer, layer 0, Defpoints and xref-dependent layers cannot be deleted until conditions are removed.
Layer tools
- LAYISO — isolates selected objects' layers (others locked/faded or off); LAYUNISO restores.
- LAYOFF / LAYON, LAYFRZ / LAYTHW, LAYLCK / LAYULK.
- LAYMCUR — makes the selected object's layer current.
- LAYMCH — changes selected objects to a destination layer.
- LAYWALK — steps through layers to view their contents.
- LAYMRG — merges layers.
- Layer states — save and restore combinations of layer settings.
- Layer filters — property filters and group filters for large layer lists.
Typical civil drawing layers (example)
A-WALL, A-DOOR, A-WIND, A-STAIR, A-FURN, A-HATCH, A-DIMS, A-TEXT, S-COLS, S-BEAM, S-REBAR, C-GRID (centre lines, CENTER linetype), P-PLUMB, E-ELEC, G-TITLE.
Blocks
A block is a named group of objects combined into a single object, stored once in the drawing's block definition table and inserted many times as block references.
Advantages
- Reuse of standard items — doors, windows, furniture, sanitary fittings, north arrows, title blocks, section marks, trees, cars.
- Smaller file size — geometry defined once.
- Global updates — redefining a block updates all insertions.
- Attributes attach data (e.g. door number, size) for schedules.
- Consistency and speed.
Creating and inserting blocks
| Command | Function |
|---|---|
| BLOCK (B) | Creates a block within the current drawing — name, base point (insertion point), objects (retain/convert/delete), units, annotative, allow exploding |
| WBLOCK (W) | Writes a block or objects to a separate .dwg file for use in other drawings |
| INSERT (I) | Inserts a block — insertion point, scale (X, Y, Z), rotation, explode option; Blocks palette in recent versions |
| BEDIT | Opens the Block Editor to modify a definition — all references update |
| REFEDIT | In-place editing of blocks/xrefs |
| EXPLODE | Breaks a block reference into its component objects |
| PURGE | Removes unused block definitions (and layers, styles) |
| BASE | Sets the insertion base point of a drawing |
| RENAME | Renames blocks, layers, styles |
Best practice: create block geometry on layer 0 with properties ByBlock/ByLayer, choose a logical base point (e.g. hinge corner of a door, centre of a column), and draw at 1 unit size for scalable blocks (e.g. a 1 × 1 door block scaled to the opening width).
Attributes
- ATTDEF defines attributes — tag, prompt, default value, modes (Invisible, Constant, Verify, Preset, Lock position, Multiple lines), text settings.
- Attributes are included when creating the block; values are entered at insertion.
- ATTEDIT/EATTEDIT edits values; BATTMAN manages attribute definitions; ATTSYNC updates references.
- DATAEXTRACTION (and older ATTEXT) extracts attribute data to tables or spreadsheets — e.g. door/window schedules, equipment lists.
Dynamic blocks
- Blocks with parameters (linear, polar, rotation, flip, visibility, lookup, alignment, array) and actions (stretch, move, scale, rotate, flip, array) defined in the Block Editor.
- One block can represent multiple sizes or configurations — e.g. a door block adjustable to 750/900/1000 mm widths with flip for swing direction.
Nested blocks
Blocks can contain other blocks (e.g. a toilet block containing WC and basin blocks).