A0, A 1, A2, A3 and A4 have the same width, all of which are 180mm, while there are two kinds of heights, the national standard is 56mm, and the machine standard and most other standards are 45mm.
The mark in the title bar is: the design of the drawing may be changed after it is implemented. If there is a change (usually a scratch), draw a change symbol at the change place, which is called "mark", usually expressed in English letters. Fill in this symbol in the mark column, and if there are multiple changes at the same time, fill in the total number of multiple places in the number column.
If it is changed again, the used symbols shall not be used in the changed part of the drawing, and other requirements are the same as above.
When changing, there should be the signature and date of the person who changed it, and there should be the number of the changed file, that is, the number of the changed file, which is the basis for the change.
The machine standard is the standard of the Ministry of Machinery Industry and belongs to the industry standard. Both national standard and machine standard are acceptable. In order to standardize, enterprises only choose one of them, and some enterprises also formulate their own standards (belonging to enterprise standards).