Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
In space groups possessing polar rotation axes, it is possible to index reflections in two (or more), non-equivalent ways. Both ways are correct, but if data are measured from more than one crystal, the indexing scheme has to be the same for all contributing parts.
