Without a standardized undercut (groove), two problems occur:

If you are designing a part or checking a measurement:

Per utilizzare la tabella GOLA, segui questi passaggi:

is the Italian adoption of the international standard ISO 4755:1983 – Fasteners – Bolts, screws and studs – Undercuts for metric threads . It replaces older national standards (e.g., UNI 4749) and aligns with modern ISO thread systems (e.g., ISO 68-1, ISO 261, ISO 965).