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.
Longitudinal (A). Transverse (B). Crosslinks are shown in orange. Note that crosslinks are not to scale and are drawn to illustrate domain crosslinking. α chains are shown in blue, β chains are shown in green, and γ chains are shown in red. For simplicity, αC interactions are excluded in this illustration.
