This part of Bs 4999 specifies the dimensions of rotating electrical machines which are outside the scope of Bs EN 50347. rt specifies the dimensions of skirt-mounted motors, pad-mounted motors, slide rails, shaft extensions with two tapped holes, and foot-mounted frames for d.c. machines. rt also specifies the dimensions of foot-mounted motors, flange-mounted motors, shaft ends and keyways, and shaft extensions with single tapped holes, all of which are above the size range covered by Bs EN 50347.