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Text Style: Select the Text style for the dimension. Text styles are specified in the Style Manager.
Height: Sets the height of the dimension text.
Font: Specifies the font use in the dimension text.
Color: Sets the color of the dimension text.
Frame around text: Draws a rectangular frame around the dimension text.
Fill Color: Specifies a color which will fill the text frame. The options are: None, Background and Custom. Background fills the frame with the background color. Custom allows you to select a color.
Text Position: Controls the dimension text position:
Text Movement: These options control how the dimension text is moved when editing the dimension. See Editing Dimensions
Horizontal: Select the text alignment with respect to witness lines. The preview window displays each option. Options vary for dimension and leader text.

Dimensions - Centered

Dimensions - First Extension Line

Dimensions - Second Extension Line
Dimensions - Over First Extension Line

Dimensions - Over Second Extension Line

Leaders - Default Justification(Depends on the leader orientation)

Leaders - Center Justification

Leaders - Left Justification

Leaders - Right Justification

Vertical: Select the text alignment with respect to the dimension/leader line. Outside places the text on the side of the dimension/leader line opposite the selected dimension/leader points.

Above

On Line

Outside

Text Gap: The distance between the dimension text and the dimension line.
Adjustment: Available for VerticalOnLine position, The distance of the text above or below the dimension line. A value of zero (default) will place the text on the same level as the dimension line. Higher values move the text above the line; lower (negative) values move the text below the line.
Force Text Horizontal: Makes the dimension text horizontal no matter how the dimension is rotated.
Force Text Inside Extension Line: Keep dimension text between the extension lines, regardless of the distance between the extension lines. If unchecked, the system will decide where to place text.

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With a dimension (or dimension tool) selected, you can go to the Selection Info palette, and under the Text-Transformation area you can specify that the text be non-rotatable.