Function Entry: NOT

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Function Entry: NOT

Name

not

Class

Function

Syntax

(not expr)

Arguments and Values

  • expr: expression

Description

Tests whether expr evaluates to nil.

Return Values

  • T if the expression evaluates to nil
  • nil otherwise

Side Effects

Side effects are those of evaluating expr.

Exceptional Situations

Any error arises from evaluating expr.

Examples

  • (not nil) => T
  • (not 1) => nil

Compatibility

Behaviorally aligned with null in documented AutoLISP usage.

Availability

  • AutoCAD 2026: documented (per Autodesk reference page).
  • BricsCAD V26: presumed compatible (no contradicting page found).
  • Status: AutoCAD documented; BricsCAD presumed-both pending Phase 4 verification.