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/etc/profile contains the default account configuration information for the /bin/sh shell,much like /etc/csh.* for csh and tcsh users. Whenever a /bin/sh user logs in, he inherits what's in this file. Users can override /etc/profile with their own .profile. Bash and other sh derivatives also use this file.
While tcsh is the standard FreeBSD shell, sh and derivatives (particularly bash) are quite popular. Consider keeping settings in /etc/profile and /etc/csh.login synchronized to ease troubleshooting in the future.