Zotero

A CSL style consists of the following elements:

• the root element : CSL version and global parameters.
• the style metadata
• the formatting of in-text or notes citations
• the formatting of the bibliography
• the macros, which allow you to write a sequence of instructions once, and reuse it several times Using macros is highly recommended.
• , to specify some terms or formatting options
• , to define the rendering of certain terms.

They allow the ordering and formatting of  bibliographic metadata elements.

• Text , which can be a , a , a , or a .
• Date , which can be the publication or access date, and date parts , for formatting day, month, year or date ranges.
• Names , for formatting names of authors, editors, publishers.
• Number , for formatting numeric variables, such as issue or volume numbers.
• Label , to format certain types of data ("vol." or "volume", for example).
• Group , to specify delimiters or formatting for a group of elements. Particularly useful to avoid this kind of thing: New York, NY: , 1990, which can occur when one element is missing in the reference (in this case the publisher). 
• Choose for conditionals (if, else-if, else).