[iliaal]

Summary

• Document the existing name string in ExcelSheet::getIndexRange()'s seven-key return array.
• Clarify its zero-based index and false result when no range exists.
• Add an Unreleased documentation note. No runtime or API changes.

Validation

• Fresh native shared-library build: PHP 8.4.26 NTS / LibXL 5.2.0.1 trial, with -Wall -Wextra -Werror -Wstrict-prototypes and the existing unused-parameter allowance; zero diagnostics.
• Full PHPT suite: 261 total, 254 passed, 7 skipped, 0 failed, 0 warned.
• All 12 PHP API reference files lint successfully.
• Focused XLS and XLSX probes pass for the exact seven-key array, zero-based index, and missing-index result.
• Documentation-contract assertion fails on the baseline missing name, passes on this change.
• git diff --check, independent review, and clean merge-tree against current master pass. No open sibling PRs.

Limitations

Local build uses retained PHP headers/configuration and LibXL rather than a fresh phpize/configure install. Local checks cover Linux PHP 8.4 only; platform/version coverage is left to repository CI. Seven platform/license-specific PHPT skips are not passes. No performance claims.