California now legally recognizes a third gender option.

Under the state's new Gender Recognition Act, which was signed on Sunday, trans and gender-nonconforming Californians can identify as nonbinary on all government-issued IDs and state documents, including birth certificates and driver's licenses.

Under the new regulations, residents can choose to self-identify as nonbinary, or "X", a gender alternative to male ("M") or female ("F"). It also simplifies the process of changing gender markers on state documents and government-issued IDs.

California defines nonbinary as "an umbrella term for people with gender identities that fall somewhere outside of the traditional conceptions of strictly either female or male."

The legislation's passage into law was met with mixed reactions.

"Society forces people into boxes & tells us who we’re supposed to be," state senator Scott Weiner wrote on Twitter. "[This law] helps people of all gender identities be their authentic selves."

"Everyone should be able to have IDs that match who they are," added Senator Toni Atkins.

But Randy Thomasson, director of the anti-LGBT group Save California, criticized the move as fostering a "delusion."

"The new birth certificate of 'female' or 'nonbinary' for a biological boy, or 'male' or 'nonbinary' for a biological girl, will 'lock in' the child's delusion more than ever," Thomasson wrote in a statement.

The Gender Recognition Act will go into effect in 2019.

In June, Oregon began to recognize nonbinary status on driver's licenses.