Publisher.
#420 電子科技大學出版社|9dian zi ke ji da xue chu ban she
#420 American Bible Society
#420 [中國醫藥學院]|9zhong guo yi yao xue yuan
#420 北九州中國書店|9kitakyuushuu chuugoku shoten_j
There may be parallel publisher statements. These are expressed in ISBD. Remember that the romanisation in subfield |9 always comes last:
#420 文物出版社 = Cultural Relics Publishing House|9wen wu chu ban she
#420 中國世界語出版社 = China Esperanto Press|9zhong guo shi jie yu chu ban she
If the function of the publisher is other than simply publication, this is noted in subfield |f:
#420 台灣銀行|f發行|9tai wan yin hang
ISBD: 台灣銀行[發行]
The field may be repeated if there is more than one publisher in the same place (or places):
#410 上海|9shang hai
#420 上海古籍出版社|9shang hai gu ji chu ban she
#420a上海書店|9shang hai shu dian
ISBD: 上海 : 上海古籍出版社 : 上海書店
To date (15 January 2016), 606 items have two publishers in the same place (or places), 48 have three, and one even has four.
For the handling of multiple place : publisher groups, see field #411&c