Alternative Writ:
“(1827) A common-law writ commanding the person against whom it is issued either to do a specific thing or to show cause why the court should not order
it to be done.”[1]
Optional Writ:
“(18c) At common law, an original writ issued when the plaintiff seeks specific damages, such as payment of a liquidated debt. The writ commands the
defendant either to do a specified thing or to show why the thing has not been done.”
Also see Writ of Mandamus
References:
[1]: All definitions from: Black’s Law Dictionary Deluxe Tenth Edition by Henry Campbell Black & Editor in Chief Bryan A. Garner. ISBN: 978-0-314-62130-6
[2]: James L. High, A Treatise on Extraordinary Legal Remedies § 2, at 5-6 (1884).