Space is the boundless extent in which events occur and have relative position and direction. Space is often conceived and considered, with time, to be part of the boundless four-dimensional continuum known as spacetime. The concept of space is considered to be of fundamental importance in gaining understanding of the physical universe.

An underscore is generally defined as a piece of background music, usually designed as a mood enhancing accompaniment to a situation. Underscores generally lack strong melody lines in order not to detract concentration too far from a focus. Underscores assist in building an atmosphere. There is no defined format to an underscore, though they generally consist of a simple drone or chord progression.

Ci (simplified Chinese: 词; traditional Chinese: 詞; pinyin: cí, interchangeable with 辭) is a kind of lyric Chinese poetry. For speakers of English, the word "ci" is pronounced somewhat like "tsuh". It is also known as Changduanju (長短句/长短句 "lines of irregular lengths") and Shiyu (詩餘/诗馀 "that which is beside poetry").

Typically the number of characters in each line and the arrangement of tones were determined by one of around 800 set patterns, each associated with a particular title, called cípái 詞牌. Originally they were written to be sung to a tune of that title, with set rhythm, rhyme, and tempo. Therefore, the title may have nothing to do with its contents, and it is common for several ci to appear to have the same title. Some ci would have a "subtitle" (or a commentary, sometimes as long as a paragraph) indicating the contents. Sometimes, for the sake of clarity, a ci is listed under its title plus its first line.

Ci most often express feelings of desire, often in an adopted persona, but the greatest exponents of the form (such as Li Houzhu and Su Shi) used it to address a wide range of topics.