Typography is the structural backbone of any visual identity. Selecting a technically flawed typeface can compromise even the most powerful design. To evaluate digital fonts, one must look beyond aesthetics and delve into Type Engineering, technical performance, and visual durability.

1. Engineering & Technical Metrics

These benchmarks define the professional integrity of the font's underlying architecture:

■ Bézier Continuity: Curves must be smooth and precise, utilizing the minimum number of nodes to ensure efficient rendering and clean outlines.
■ Optical Corrections: Implementing "Overshoots" for rounded forms to ensure visual alignment and adjusting the "Optical Center" to achieve balanced mass.
■ Spacing & Kerning: A professional typeface includes thousands of manually tuned kerning pairs to correct irregular gaps, especially in complex Arabic ligatures.

2. Programming Robustness & OpenType Features

Scripting is what separates professional-grade typefaces from simple hobbyist fonts:

■ Advanced Feature Support: Full compliance with GSUB and GPOS tables to manage contextual substitutions and precise Mark Positioning (diacritics).
■ Interpolation Integrity: In Variable Fonts, the transition between masters must be mathematically sound, ensuring no structural glitches in the design space.
■ Hinting: High-quality fonts incorporate sophisticated hinting to optimize legibility on low-resolution displays.

3. Systematic Consistency & Multilingual Harmony

■ Bilingual Integration: Achieving a precise visual match in "weight" and "x-height" between Arabic and Latin scripts for seamless bilingual typesetting.
■ Character Set Completeness: Ensuring the font covers a wide range of glyphs, symbols, and currencies, as well as extended language support (e.g., Persian and Urdu).

4. Functionality & Legibility

Aesthetics should never overshadow utility. A successful typeface maintains high legibility in small body text sizes and provides clear differentiation between similar characters while conveying a distinct "Tone of Voice" suitable for the design’s message.

Pro Tip: Never test a font in isolation; evaluate it in running text. Prioritize fonts with clear Licensing and professional documentation, as a well-engineered typeface is a long-term technical investment.