Layers: organising a drawing

Think of layers as transparent sheets stacked on top of each other. Walls on one, doors on another, dimensions on a third. Because each object belongs to a layer you can:

• switch groups of objects on and off (show a furniture layout, hide it for the structural engineer);

• control how they print — heavy lines for cut walls, thin grey lines for furniture;

• select everything of one kind instantly;

• share drawings that other people understand at a glance.

A drawing with everything on one layer is technically complete but practically unusable.

Use a consistent, descriptive standard — most offices have one. A common pattern (from the US National CAD Standard) is Discipline-Major-Minor: A-WALL, A-DOOR, A-FURN, A-ANNO-DIMS, S-GRID. Other countries use ISO 13567-style names. What matters is that names are consistent, sort sensibly and tell a stranger what's on them.

• Layer 0 exists in every drawing and can't be renamed. Don't draw on it — except inside block definitions, where objects on layer 0 take on the layer of the block reference.

• Defpoints is created automatically when you dimension. It never plots. Don't draw on it by accident.

• ByLayer: set colour, linetype and lineweight of objects to ByLayer so they follow their layer. Override them only for a clear reason — overrides are what make drawings inconsistent.

LAYISO isolates the layer of a selected object; LAYUNISO restores. LAYOFF turns off a picked object's layer. LAYMRG merges layers. Layer States save and restore a combination of on/off/frozen layers — useful for switching between presentation and construction views.