There are several metadata can be set to a card, list as below:
@taxon{...}it accepts a text@title{...}it accepts a list of forms@author{...}it only accepts a card address@author/literal{...}it accepts a text@date{...}it accepts a text, but I suggest inyyyy/mm/ddformat@toc/depth[n]it accepts an integer, which is the depth of generated TOC, the default value is2