Fits are rated at standard reference temperatures (typically 20°C). An interference fit will act very differently on a hot summer shop floor compared to a cold inspection room.
When you see a callout like , here is what it means: iso 286 pdf
standard, titled "Geometrical product specifications (GPS) — ISO code system for tolerances on linear sizes," is the fundamental global reference for hole and shaft fits in engineering and manufacturing. ISO - International Organization for Standardization Fits are rated at standard reference temperatures (typically
: You can view the official abstract and terminology on the ISO Online Browsing Platform (OBP) . here is what it means: standard
(A–ZC) are used for internal features ( holes ).