The plane rectangular coordinate system used in measurement is basically the same as that in mathematics, but the coordinate axes are interchanged and the quadrant order is opposite. The longitudinal axis is x, which is consistent with the north-south direction, with the north being positive and the south being negative; The horizontal axis is the Y axis, which is consistent with the east-west direction, and the east is positive and the west is negative. Directional measurement of homeopathic needle.

The measurement standards recognized by international agreements serve as the basis for setting other quantitative measurement standards internationally. The measurement standards recognized by the state should be used as the basis for formulating other measurement standards related to quantity in a country. It has the highest measurement characteristics, and its value does not need to refer to other standards, designated or recognized measurement standards of the same amount.

Measurement standards refer to physical measuring tools, measuring instruments, reference substances or measuring systems that are used as units or references for defining, realizing, saving or reproducing quantities.

Extended data:

A group of similar physical measuring tools or measuring instruments are used in combination to form a standard, which is called a collective standard.

A set of standards for selected values, which can be used alone or in combination to provide a series of values with the same number, is called a standard group.

Benchmark: a physical measuring tool, measuring instrument, reference substance or measuring system used as a reference in order to define, realize, save or reproduce the unit or one or more values of quantity.

Example:

(1) 1kg quality standard;

(b)100Ω standard resistance;

(c) standard ammeter;

(d) Cesium frequency standard;

(e) standard hydrogen electrode;

(f) Reference solution with certified cortisone concentration in plasma.

note:

(1) A group of similar physical measuring tools or measuring instruments, and the standards formed by their joint use are called collective standards.

(2) A set of standards whose values have been selected can be used alone or in combination to provide a series of values with the same number, which is called a standard set.

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