ASME-USCTI-DIN-JIS-ISO SPECIFICATIONS:

More and more Metric specifications are showing up on manufacturing prints
in the USA. To help clarify abbreviations we offer explanations below:

ASME/USCTI: USA Tool Standards.
American Society of Mechanical Engineering / United States Cutting Tool
Institute, all standards are specified in the Imperial measurement (Inches).

DIN: German Standard
Deutsches Institut Fur Normung / German Institute for Standard, all
measurements are to the Metric system.

JIS: Japanese Standard
Japanese Industrial Standard, all measurements are to the metric system

ISO: Global
International Standardization Organization, all measurements are to the
metric system.

Other countries have their own standards that would relate to specific
industries like aircraft and automotive applications. By way of example, in
the USA other standards like NAS - National Aero Space. SAE - Society of
Automotive Engineers are related to specific of industries.

Here are some examples of differences in Metric Jobber Drills versus an Inch
Jobber Drill:

1) A metric drill OAL is measured from back of shank to point tip of the
drill; an inch drill is measured from back of shank to point shoulder.

2) OAL on a standard jobber DIN drill (specified as DIN 338) can be shorter
than an Inch jobber drill. You need to be vigilant when specifying because
DIN Flute lengths are a lot shorter and if using an inch drill bushing your
flutes could still be inside the bushing preventing chips from being
evacuated.

3) Metric Drill OD tolerances are measured in lower case letters such as h8.
Inch sizes, on the other hand, would be +. 0 to a minus tolerance.

4) Metric tangs are also different and will not fit into an inch collet.