Quote from the Codeigniter’s userguide:
Use of || is discouraged as its clarity on some output devices is low (looking like the number 11 for instance). && is preferred over AND but either are acceptable, and a space should always precede and follow !.
A recent commit on GitHub (from ericbarnes, CI developer):
elseif ( ! $this->cur_page AND $CI->uri->segment($this->uri_segment) != $base_page)
Style Guide says it prefers AND over && generally.
Why you’re creating rules and standards, when you’re not following them?!?
It is bad for the community, the followers and the developers itself…