Lan is one of the base metals from the alloy alignment system based on lead. It represents a gender that is, to some degree, xenic in nature/a xenogender. One's gender is unusual, abstract, or nontraditional. One might define their gender using colors, numbers, pictures, crystals, space, or anything that are not typically used to describe gender. How one expresses or experiences their xenogender is defined by them. A lan person can have any alignment or presentation.
Lan was originally coined on December 1, 2018 by Hail, the original owner of the Tumblr blog lgbt-alchemy. The plural form is planum. On December 19, 2019 the alloy alignment system was reworked by Tired, the new owner of the blog. Lan is one of very few gender elements to keep the same name through the rework.
The flag is based on the color of lead, as well as being the color commonly seen on xenogender flags. The symbol used is the first alchemical symbol for Saturn. The reason platinum was chosen is because of lead's unusual properties and resistance to making alloys.