Identify the standard line type: which line pattern consists of three dashes—one long dash, a short dash in the middle, and another long dash—used to indicate axes and centers on engineering drawings?

Introduction / Context:
Line conventions encode meaning without words. Recognizing line types—object, hidden, center, phantom—is essential for reading and creating unambiguous drawings.

Given Data / Assumptions:

• Pattern described: long dash – short dash – long dash (repeating).
• Use case: indicating axes of symmetry, hole centers, bolt circles.
• Standard drafting conventions are assumed.

Concept / Approach:
A center line uses alternating long and short dashes. Hidden lines are short, evenly spaced dashes; object lines are continuous thick lines; phantom lines are long–short–short repeating and show alternate positions or motion paths.

Step-by-Step Solution:

Verification / Alternative check:
Check a standard drawing legend: center lines are long–short repeating; when drawn as a three-dash snippet, it appears as long–short–long.

Why Other Options Are Wrong:

• Object: solid continuous line, shows visible edges.
• Hidden: equal short dashes, indicates obscured edges.
• Phantom: long–short–short repeating; used for alternate positions.

Common Pitfalls:
Confusing phantom with center. Remember phantom has two short dashes between long dashes; center has a single short dash between long segments.

Final Answer:
Center