Dimensions, Tolerances, and Annotation Scaling
Dimension styles
DIMSTYLE controls the geometry and text of dimensions through a parent style plus child styles for linear, angular, radius and diameter. Key variables include DIMSCALE (overall size factor), DIMLFAC (measurement multiplier), DIMTXT (text height) and DIMASSOC (2 = associative, so dimensions update with geometry; use DIMREGEN if they do not). Tolerances sit inside the style: DIMTOL adds plus/minus values (DIMTP, DIMTM), DIMLIM produces limit dimensions, and symmetric tolerances use equal plus and minus values. Geometric tolerances are separate objects created with TOLERANCE as feature control frames.
Annotation scaling
Annotative objects store a paper height and a list of scales; at each scale the object displays at the right size. Annotation scale is set on the model space or viewport scale list, ANNOALLVISIBLE shows objects at all scales, and ANNOAUTOSCALE set to 0 stops AutoCAD adding scales to every annotative object as you change viewport scale. Linetype appearance is controlled by LTSCALE, CELTSCALE, MSLTSCALE and PSLTSCALE; model space linetypes need MSLTSCALE = 1 to match annotation scale.
Worked example
A dimension placed in paper space over a 1:50 viewport reads 20 instead of 1000. The viewport shows 50 model units per paper unit, so set DIMLFAC to 50 in that dimension style. The cleaner alternative is to dimension in model space with an annotative style carrying the 1:50 scale.
Traps
Overrides that fix one dimension but leave the style wrong; dimensioning in paper space without DIMLFAC; mixing annotative dimensions with a fixed DIMSCALE; piling scales onto annotative blocks until grips and selection multiply.