What changes between the two systems?
Autodesk's AutoCAD 2026 documentation distinguishes CTB color-dependent tables from STB named tables. CTB uses object color to determine plotting characteristics, while STB allows different named styles for objects with the same color. Named styles can be assigned to objects or layers.
DWG Conversion is independent and is not affiliated with Autodesk. This guide is a migration verification worksheet, not a command sequence or authority to replace the receiving project's approved plotting standard.
What should the sample comparison retain?
Preserve a source DWG, its plot table and a baseline output made with the documented layout settings. Work on a controlled copy. Record the target table and assignments instead of assuming that a similarly named table has identical settings.
| Comparison field | Before migration | After migration |
|---|---|---|
| Drawing system | Recorded CTB or STB basis | Approved target system |
| Style table | Exact supplied table file | Exact selected target table |
| Assignment | Object color and relevant properties | Named style or approved color mapping |
| Layout | Paper, scale and plot settings | Same comparison basis or documented change |
| Output sample | Controlled baseline PDF | Candidate PDF and observed differences |
| Disposition | Receiving standard and owner | Accepted mapping or unresolved difference |
How can color matching conceal a plotting change?
Illustrative example. In a fictional baseline, two red electrical drawing objects use the same CTB plotting rule. In the migrated STB copy, one has a named style called Main and the other a named style called Secondary. The screen still shows red for both; their target styles need not produce the same lineweight.
The reviewer checks the actual style definitions and compares the plotted objects, labels and symbols against the approved standard. The style names and example are synthetic and imply no universal lineweight convention.
Do not fix the difference by changing every red object without identifying the intended mapping. That can hide an assignment problem and alter other layouts.
What closes the migration check?
Check representative linework, symbols, text and any deliberately screened content in the generated output. Record accepted changes as well as defects. A PDF that opens successfully does not prove the plotting semantics were preserved.
Keep the final DWG, table file, layout references, sample output and mapping approval together. Repeat the sample when a table or style assignment changes. For technical electrical content, engineering sign-off is performed only by the registered engineer on the job.
Common questions
What else should the bid team know?
Can two objects of the same color plot differently under STB?
Yes, when different named styles are assigned.
Is copying a table file the complete migration?
No. Verify the drawing system, assignments, layout selection and actual output.
Does this guide replace the project CAD standard?
No. The approved receiving standard controls the mapping.