Best practice when creating custom blocks: avoid putting geometry on annotation or special-purpose layers When creating your own blocks for reuse across drawings, it is important to avoid drawing any portion of the block on which one of the following specific layers?

Introduction / Context:
Layer discipline is critical for reusable content. Blocks that carry fixed layer assignments for their internal linework can behave unpredictably when placed on different layers in host drawings. This question focuses on which kind of layer should be avoided when building general-purpose blocks.

Given Data / Assumptions:

• We are creating general-purpose, reusable blocks (doors, fixtures, symbols).
• We want the block to inherit properties (color, linetype) from the layer on which it is inserted.
• Annotation and special-purpose layers exist in the project, e.g., center line, hidden, hatch.

Concept / Approach:
Best practice is to create block geometry on Layer 0 with all properties set ByLayer or ByBlock. This allows the block to take on the color, linetype, and lineweight of the insertion layer. Conversely, placing any portion of the block on dedicated layers such as “center line” locks that geometry to those layer properties and visibility. If that special layer is turned off or frozen, parts of the block disappear unexpectedly.

Step-by-Step Solution:
Identify layers intended for annotations or specialty graphics (center lines, hatches, hidden lines).Recognize that internal block entities on those layers will not inherit host-layer settings.Conclude that such layers should be avoided for internal block geometry.Among the options, “center line” represents that class and is the correct answer.

Verification / Alternative check:
Insert a test block drawn on Layer 0 into varied layers and observe that its properties adapt automatically. Compare with a block containing entities on “center line”; turning off that layer hides portions of the block, confirming the risk.

Why Other Options Are Wrong:

• Layer 0: Recommended for block creation to enable property inheritance.
• Hatch / hidden line: Also poor choices, but the question asks for a single layer; “center line” represents the principle of avoiding special-purpose layers.

Common Pitfalls:
Mixing multiple fixed layers inside blocks; forgetting to use ByLayer/ByBlock properties; embedding annotation (text/dimensions) into model blocks.

Final Answer:
center line