Document preferences returning wrong values

Hey!

I just found here is the problem!

If you select predefined sizes, you get decimal values,

but if you enter size manualy, then all is ok.

So, It's bug in InDesign...

tomaxxi

(1) InDesign does not store its measurements in the format you enter (or, in this case, taken from an internal list). Everything is converted to points internally. While this reclaculating is done with 15 decimals' worth of accuracy, some rounding will always occur.

(2) InDesign uses a "double" decimal storage format. Decimals cannot be lossless stored into this format -- compare it to expressing 1/3 in decimals ... The good news is, this storage format defines 52 bits for storing the decimals, and that's enough for 15 significant decimal digits. Not surprisingly, exactly the number of significant digits you got (perhaps Javascript is rigged not to return any more, as that would be meaningless).

(3) A4 is *not* exactly equal to 210 x 297 mm. A0 is defined to be exactly 1 square meter, with a length to width ratio of the square root of 0.5 (about 0.7071). Each next A-step down halves the size, so an A4 is defined to have a surface of exactly 1/16 m². Using the size ratio, that would come down to exactly  (sort of)  210.22 mm x  297.302 mm, with loads and loads of less significant decimals. However, that's the official definition!