The big seal script of character Flat is
is character 户 - Household (Post 271),
is character 册 - Book (Post 62), a connected multiple writing bamboo slips, which is very thin and flat.
The character original means door plaque, which is a board with brush writing hanging on the door. In ancient time, it was bamboo book.
As time past, it represents Flat more often, people created another character
The clerical script of the character Flat is
The song typeface of the character is
Very similar to clerical script.
The pinyin of the character is Bian3.