Layouts, Viewports, and Plotting
Layouts and viewports
Model space holds full-size geometry; a layout is paper space measured in millimetres or inches at 1:1. MVIEW creates a viewport, and its scale is set from the standard scale list or the Viewport Scale control; lock the viewport once the scale is correct so accidental zooming cannot change it. Non-rectangular viewports come from MVIEW > Polygonal and can be reshaped with CLIP. Viewport-level overrides - VP Freeze, VP colour, VP linetype - are stored per viewport and are the correct tool when one sheet must differ from another.
Plotting
PAGESETUP records plotter, paper size, plot style table, plot area (Layout, Extents, Window, Display), plot scale, offset and orientation. Colour-dependent plot style tables (.ctb) map colours to lineweights; named plot style tables (.stb) map named styles, and PSTYLEMODE reports which a drawing uses. Layouts normally plot at 1:1; Fit to paper silently rescales and is the usual cause of a sheet that measures wrong. PUBLISH batches sheets with their own page setups, and a sheet set can publish or eTransmit an entire set at once.
Worked example
A 1:100 plan on A1 must also be issued on A3. Plotting the A1 layout to A3 paper halves everything, so the printed scale becomes 1:200 and every note shrinks to 50%. The correct fix is a second layout on A3 paper with a viewport set to 1:200 and annotation sized for the smaller sheet.
Traps
An unlocked viewport zoomed after scaling; a missing .ctb so lineweights print wrong; plotting Extents when stray objects sit outside the sheet; assuming viewport scale equals plot scale on a Model-tab plot.