Verbiage from USCIS news link.
Eligible individuals include certain H-4 dependent spouses of H-1B nonimmigrants who:
- Are the principal beneficiaries of an approved Form I-140, Immigrant Petition for Alien Worker; or
- Have been granted H-1B status under sections 106(a) and (b) of the American Competitiveness in the Twenty-first Century Act of 2000 as amended by the 21st Century Department of Justice Appropriations Authorization Act. The Act permits H-1B nonimmigrants seeking lawful permanent residence to work and remain in the United States beyond the six-year limit on their H-1B status.