assumed decimal point
Computing term for a decimal point whose position is implied by the data format rather than explicitly stored.
In fixed-point arithmetic, the programmer must be aware of the assumed decimal point position.
固定小数点 (fixed point) is a broader concept; 想定小数点 specifically refers to the decimal point that is assumed but not stored.
浮動小数点 (floating point) explicitly stores the exponent, making the decimal point position variable, unlike the fixed, assumed position in 想定小数点.
Compound of 想定 (assumption) + 小数点 (decimal point), literally 'assumed decimal point'. A technical term from computing.