1.   Rick wrote the following about the computer program; "ISOTOL interfaces just fine with AutoCAD. The software works just fine with MDT. It is straight forward and easy to use. It is a simple program that would be of great value to anyone that needs to figure tolerancing".  Rick Novara ricknovara@compuserve.com ; Phone 704 921 0303 ; Fax 704 921 0304 , Novara Engineering
12325 Mallard Ridge Drive, Charlotte NC 28269.

Industry Users of Metric Standards Book, Software’s or Training Program

Sizes

Preferred Basic Sizes .
The first choice sizes follow approximately the preferred number series R5 where succeeding numbers in the series increase by 60% . The second choice series shown are rounded off from the R10 series of preferred numbers (25% increments) . Third choice sizes shown are rounded off from the R20 series of preferred numbers (12% increments) . The basic sizes conform to the ISO 497 R"20 rounded series. The preferred numbering system is important to use when selecting sizes in the metric system . The French army captain , Charles Renard , was able to reduce the number of different rope sizes used in army balloons from .. 425 .. to .. 17 , with the aid of the series . The preferred number series are designated R5 , R10 , R20 , etc . after the French army captain.
The selection of sizes in the metric system differ from the selection of sizes in the inch system since each inch contain 25 integer (whole) millimeter sizes in the length of one inch . The inch fractions have functioned to some extent as a rationalizing tool . The fraction 1/2 is preferred over 1/4 ; 1/4 is preferred over 1/8 ; 1/8 is preferred over 1/16 ; etc .

Fits

Preferred Fits and Tolerance Zones
Ten (10) preferred hole and ten (10) preferred shaft basis fits ranging from loose running to interference fits may be selected in the   KOK ISOTOL ™  Computer Tolerancing Software   main screen.   You will see instant display of hole, shaft and fit limits.    For special fits you may choose from 150 other hole and shaft tolerances.   The first choice tolerance zones are clearly marked (F-green), and they are those used in the ten (10) preferred fits .
The   KOK ISOTOL ™   Computer Tolerancing Software    will allow the user,  if required,  to modify the preferred fits to satisfy a special requirement.   The mating part may be changed and at the same time the user could specify one of the preferred hole tolerances ; H11 , H9 , H8 , or H7 or one of the preferred shaft tolerances ; h11 , h9 , h7 , or h6.   These tolerance zones are also preferred in the ISO 1829 standard . National standards for cold finished steel rod material reflect the four (4) preferred shaft tolerances h11 , h9 , h7 , and h6 in the largest industrial countries of the world . This is very important for rationalization purposes in industry. The potential benefits this may give USA and worldwide manufacturing,  is just immense.   It should produce even more savings than the millions of dollars gained in EU industries over the past 60 years.

Gages

Plug and ring(snap) gages to the first and second choice basic sizes and preferred fits are tabulated and specified in the ANSI B4.4M standard . Hole and shaft gages for checking the above sizes and tolerance zones are readily available (off-the-shelf) in EU countries , and gagemakers in USA will most likely keep a similar inventory of preferred gages.    See  KOK ISOGAGE™    Computer Software for Gages.