系

System Xi4

The top character is not 一 yi1 which means 1. It is the falling left stroke as an ideogram of one of the two objects which are tied together by the middle character yao 幺1 which means one, small, and is an ideogram from a silk thread (the one small silk thread as the symbol of ONE and TINY, that is 幺 yao1). The bottom character 小  is an image of a bird as a symbol of the idea of small. yao1 幺 and xiao3 小 together make mi4 糸 which means silk.

Mnemonics

Xistem

single silk string small SYSTEM TO TIE

一幺小糸系

Hierarchized
Systematic
Information = SYSTEM, TO TIE， DEPARTMENT