AbstractEmpirical accounting research often treats firm-year financial statement variables as stable measurement objects. In practice, the face of financial statements evolves: new standards introduce new line items; firms add or drop disclosure modules; and reporting regimes shift. These changes create structural breaks that can silently damage panel comparability and bias derived metrics. This note proposes a simple, reproducible diagnostic - an item-coverage table - that records which line items appear in which years, allowing researchers to identify a consistently reported backbone set of items and to segment analysis when economically important items are regime-bounded. Using Westshore Terminals annual financial statements from 2010 to 2022, yielding 2009 to 2022 via comparatives, as a worked example, the diagnostic separates a stable backbone of revenue, expense, and working-capital items from era-dependent modules such as IFRS 16 lease items and mid-panel arrivals including deferred revenue, buybacks, and capex unpaid. Keywords comparability; structural breaks; IFRS 16; lease accounting; disclosure diagnostics; panel construction; item coverageJEL codes M41; M48; G31; G32; G35

Item-coverage diagnostics make structural breaks in multi-year financial statement panels explicit by publishing a canonical coverage table and derived era-module and feasibility views, demonstrated with Westshore Terminals where IFRS 16 leases, deferred revenue, buybacks, and capex-unpaid items define distinct measurement eras.