iso tool shank standard is: IS07388/1 for international standards.
iso standard refers to the standards developed by the (international organization for standardization).
iso's predecessor is the international association for standardization (ISA),
ISA was founded in 1926 (1926, the United States, Britain,
Canada and other seven countries standardization body of the third joint meeting of
the representatives of the decision to set up the international association for standardization,
and was established in 1928). The outbreak of the Second World War forced ISA to stop working.
After the end of the war, the general environment provided conditions for industrial recovery, so in October 1946,
leaders from 25 national standardization bodies met in London to discuss
the establishment of the International Organization for Standardization (ISO),
and called the new organization ISO, short for International Organization for Standardization.
The meeting unanimously adopted the constitution and rules of procedure of ISO,
and on February 23, 1947, ISO began its formal operation, with its central office located in Geneva,
Switzerland. China was both the initiator and the first member.

There are five standards and specifications for universal toolholders with a 7:24 taper,
namely NT (traditional), DIN 69871 (German standard), IS07388/1 (international standard),
MAS BT (Japanese standard) and ANSI/ASME (American standard).

ISO 7388/1 (IV or IT) has the same shank mounting dimensions as DIN 69871,
but because the D4 value of ISO 7388/1 is smaller than that of DIN 69871,
there is no problem mounting ISO 7388/1 shanks on DIN 69871 tapered hole machines,
but mounting DIN 69871 shanks on ISO 7388/1 shanks is not a problem.
However, if a DIN 69871 toolholder is mounted on an ISO 7388/1 machine, there is a risk of interference.