InDesign creates PDFs with measurements to 4 decimal places.

Acrobat rounds all measurements to 3 decimal places.

We make print-ready files with measurements up to 1/32nd of an inch (0.03125"). That's 5 decimal places.

Many of our print vendors insist we use 5 decimal places. (But they accept InDesign only goes to 4.)

The issue is we go to edit things like Trim size or page size in Acrobat, and all those measurements are rounded to 3 decimals.

North American book production uses Inches for units. Our prepress production staff are now in the process of converting everything to Points, just so we can use more precise measurements.

(For extra fun: Acrobat for Web only goes to 2 decimal places!)