According to ICAO coding used historically in exam literature, runway pavement strength classifications have been represented using which set?

Introduction / Context:
Many civil-aviation examination guides summarize ICAO-related runway strength classifications using alphabetic groups for quick recall. Although modern practice emphasizes PCN/ACN codes, older question banks often ask about the alphabetic grouping used for categorization.

Given Data / Assumptions:

• Question refers to “coded by …” in a multiple-choice form typical of legacy exam material.
• Focus is on the alphabetic set used for classification (memory aid), not on detailed PCN composition.

Concept / Approach:
In legacy summaries, classifications were associated with the first seven letters (A through G) to indicate categories of load-bearing capacity or related grouping, later superseded by the fuller PCN system (which uses numbers and letters to indicate pavement type, subgrade strength, tire pressure limits, and evaluation method).

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