ISO 14405-1:2016 establishes the default specification operator (see ISO 17450-2) for linear size and defines a number of special specification operators for linear size for features of size, e.g. "cylinder", "sphere", "torus,"[1], "circle", "two parallel opposite planes", or "two parallel opposite straight lines".

It also defines the specification modifiers and the drawing indications for these linear sizes.

It covers the following linear sizes:

• local size:
  • two-point size;
  • spherical size;
  • section size;
  • portion size;
• global size:
  • direct global linear size:
  • least-squares size;
  • maximum inscribed size;
  • minimum circumscribed size;
  • minimax size;
  • indirect global linear size;
• calculated size:
  • circumference diameter;
  • area diameter;
  • volume diameter;
• rank-order size:
  • maximum size;
  • minimum size;
  • average size;
  • median size;
  • mid-range size;
  • range of sizes;
  • standard deviation of sizes.

• a + and/or − limit deviation (e.g. 0/−0,019);
• an upper limit of size (ULS) and/or lower limit of size (LLS) (e.g. 15,2 max., 12 min., or 30,2/30,181);
• an ISO tolerance class code in accordance with ISO 286-1 (e.g. 10 h6);

ISO 14405-1:2016 provides a set of tools to express several types of size characteristic. It does not present any information on the relationship between a function or a use and a size characteristic.

[1] A torus is a feature of size when its directrix diameter is fixed.