37 CFR § 42.120 - Patent owner response.
(a) Scope. A patent owner may file a single response to the petition and/or decision on institution. A patent owner response is filed as an opposition and is subject to the page limits provided in § 42.24.
(b) Due date for response. If no time for filing a patent owner response to a petition is provided in a Board order, the default date for filing a patent owner response is three months from the date the inter partes review was instituted.
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