EL Brackets to remove the original meanings of the contents

rl and rr ASCII: [ and ]
#rl is the line covering out of the left side of the frame, and #rr is the line covering out of the right side of the frame.

The hand signs:

rl
making the bracket shape with the thumb as the lower position and the index.

rr
making the bracket shape with the thumb as the higher position and the index

The function:

The character(s) in one or both of these brackets loose the meaning which originally have,
and the new symbols can be used for any definitions temporally as the users' setting.
The examples of these usage are here.

The name of both

arranged from the name {ni} of (means denied (for the original meaning)).
The vowel is extended to show there is some contents, and the phonetics of
(means 'cover, holder') positions at the end distinguishing brackets from many names of bases.

When necessary to catch plural characters, both brackets bundle them removing the original meanings.

The name of the left bracket

[nju:t]:
added the extended vowel of in the base name [su] of ( pointing the left)

The name of the right bracket :

[nje:t]:
added the extended vowel of in the base name of ( pointing the right)

For example and are used as different but similar symbols. See here for more information.