Radical 2

Radical 2 or radical line (丨部) meaning "vertically connected" is one of 6 of the 214 Kangxi radicals that are composed of only one stroke.

In the Kangxi Dictionary, there are only 21 characters (out of 49,030) to be found under this radical.

丨 is also the 2nd indexing component in the Table of Indexing Chinese Character Components predominantly adopted by Simplified Chinese dictionaries published in mainland China, with 亅 being its associated indexing component (used to be associated with 乛 prior to the new standard in 2009).

In calligraphy
The only stroke in radical line, known as 豎/竖/竪 shù "vertical", is called 努 nǔ in the eight principles of the character 永 ( Yǒngzì Bāfǎ) which are the basis of Chinese calligraphy.