What is a Plot Style Table (CTB or STB) in AutoCAD?

ByCADbrief Staff

What is a plot style Table (CTB or STB) in AutoCAD?

Short Answer

A Plot Style Table in AutoCAD controls how objects print, including lineweight, color, screening, and dithering, typically through the PLOT command. The most common professional method is using a CTB file to map object colors to print styles. Limitation: CTB and STB cannot be used interchangeably in the same drawing mode.

What You Need to Know Before

Warning: A drawing is either color-dependent (CTB) or named plot style-based (STB), and mixing standards across files can break office plotting consistency. A common failure is receiving consultant drawings in STB format when your company plots by CTB colors.

How to Use a Plot Style Table in AutoCAD

  • Command: PLOT

  • Shortcut: Ctrl+P

  • Quick Steps:

    1. Open the Output tab on the Ribbon, then click Plot in the Plot panel.
    2. In the Plot dialog, choose your printer/plotter and paper size, then select a file in the Plot style table (pen assignments) dropdown.
    3. Turn on Plot with plot styles, preview the sheet, and click OK or Apply to Layout.

Variables & Settings

  • System Variable: PSTYLEMODE (Default: 1 in CTB-based drawings)

  • Expert Setting: PSTYLEMODE shows whether the drawing uses color-dependent plot styles (1 = CTB) or named plot styles (0 = STB). This affects which plot style tables are available and whether you can assign named styles directly to objects and layers.

Why it Fails

  • Cause 1 (Geometry): Objects may be plotted with unexpected lineweights because their assigned color drives the CTB output, not their visual screen appearance alone.
  • Cause 2 (Layers/Locks): Layer overrides in viewports or locked company templates can cause plotted results to differ from the assigned plot style table.
  • Cause 3 (Command/Logic): The drawing may be in STB mode, so CTB files will not appear as valid choices until the file is converted or matched to the correct plotting standard.

Quick Fix & Best Practice

  • Quick Fix: Run CONVERTPSTYLES to convert the drawing between CTB and STB modes if the wrong plot style type is being used.
  • Manager’s Verdict: Use CTB when your office standard relies on plotting by object color, and use STB only when your team actively manages named print styles across templates and deliverables.

FAQ

What is the difference between CTB and STB in AutoCAD?

CTB uses object color to control plotting, while STB uses named plot styles assigned to objects or layers.

How do I know if a drawing uses CTB or STB?

Check the drawing with the PSTYLEMODE system variable.

Can I convert a CTB drawing to STB?

Yes, use CONVERTPSTYLES to switch the drawing’s plot style mode.

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