Shoe size "Footwear - Sizing - Vocabulary and terminology"; currently in development are companion standards ISO/TS 19409 "Footwear - Sizing - Measurement of last dimensions" and ISO/TS 19410 "Footwear - Sizing - Inshoe measurement". The adult shoe sizes are calculated from typical last length, which is converted from foot length in mm by adding an allowance of two shoe sizes: where formula_13 is foot length in mm. Direct conversion between adult UK, European and Mondopoint shoe size systems is derived as follows: Exact foot lengths may contain repeating decimals because the formulas include division by 3; in practice, approximate interval steps of
ISO image and Macintosh installations from a single disk image (by containing several file systems). An ISO can be "mounted" with suitable driver software, i.e. treated by the operating system as if it were a physical optical disc. Most Unix-based operating systems, including Linux and macOS, have built-in capability to mount an ISO. Versions of Windows after and including Windows 8 also have such capability. For other operating systems software drivers can be installed to achieve the same objective. Since there is no standard defining the ISO disc image file format, the term "ISO image" is sometimes used in a broader sense