Working with Layouts, Annotations, and Dimensions
Model space and layouts
Geometry is drawn full size in model space. Layouts (paper space) hold a title block at paper size and viewports created with MVIEW or VPORTS. Each viewport has a scale; lock the viewport display after setting it so panning does not change the scale. Page setup assigns the plotter, paper size, plot style table, and scale for the layout.
Annotation scaling
Annotative objects such as text, dimensions, multileaders, blocks, and hatches carry a list of scales and display at the size appropriate to the current annotation scale. Set CANNOSCALE to match the viewport scale before annotating, or add the scale to the object. ANNOALLVISIBLE controls whether annotation from other scales shows. MSLTSCALE makes model-space linetypes display according to annotation scale.
Dimensions and text
DIM and DIMSTYLE create and manage dimensions. A dimension style controls text height (DIMTXT), arrow size (DIMASZ), extension and offset gaps, units, and overall scale (DIMSCALE). DIMSCALE 0 means the style is annotative. DIMLFAC multiplies measured values, which is useful when dimensioning in a layout at a scale. DIMASSOC controls whether dimensions update with the geometry; non-associative dimensions are static. MTEXT and TEXT use text styles, and fields can pull in drawing properties.
Traps: setting a viewport scale by zooming rather than assigning a scale; adding annotative text at the wrong CANNOSCALE; misusing DIMLFAC instead of scaling the viewport properly; and expecting non-associative dimensions to follow edits.
Worked example: for a 1:50 layout, set the viewport to 1:50, lock it, set CANNOSCALE to 1:50, then place annotative dimensions in model space or dimension in paper space over the viewport.