Variable Entry: NIL

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Variable Entry: NIL

Name

nil

Class

Predefined value

Value Type

Distinguished object.

Initial Value

Itself.

Description

nil is the canonical false value and the canonical empty-list value.

Autodesk documentation sampled here does not describe nil as a separate type designator. Instead, it describes nil through its behavior:

  • as the value recognized by null and not,
  • as the empty list accepted by listp,
  • as a value for which (type nil) returns nil.

Affected By

  • conditional evaluation
  • list-processing functions
  • type and predicate functions

Exceptional Situations

None specific to nil as a predefined value are documented in the sampled corpus.

Examples

  • (null nil) => T
  • (not nil) => T
  • (listp nil) => T
  • (type nil) => nil

Compatibility

This entry is intentionally written as a predefined value entry, not a type entry.

Notes

This specification avoids importing the Common Lisp distinction between the nil type and the null type into AutoLISP unless vendor evidence later requires it.

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.