SVG version of one of the proposals for an enbian pride flag [first proposed by whom? please add citation if known].
The term enbian is used to describe nonbinary individuals who are attracted to, in relationship(s) with, or interested in relationships with other nonbinary people. 
The colors are those of the nonbinary pride flag: 
Yellow represents people whose gender exists outside the binary, purple is those who feel their gender is a mixture or between male and female, and the black represents people who feel as if they have no gender. The white stripe represents those who embrace many or all genders.

The gradient is sometimes thought to represent the aromantic/asexual spectrum of attraction.
Own work
Mangostaniko