ORS § 92.080
Notwithstanding ORS 205.232 and 205.234, all plats subdividing or partitioning land in a county in this state, dedications of streets or roads or public parks and squares and other writings made a part of the subdivision or partition plats offered for record in a county in this state must be made on material that is 18 inches by 24 inches in size with an additional three-inch binding edge on the left side when required by the county clerk or the county surveyor, that is suitable for binding and copying purposes, and that has the characteristics of strength and permanency required by the county clerk and county surveyor. All signatures on the original subdivision or partition plat must be in archival quality black ink. The subdivision or partition plat must be of a scale required by the county surveyor. The lettering of the approvals, the declaration, the surveyor's certificate and all other information must be of a size or type to be clearly legible, but the information may not come nearer an edge of the sheet than one inch. The subdivision or partition plat may be placed on as many sheets as necessary, but a face sheet and an index page must be included for subdivision or partition plats placed upon three or more sheets.
ORS 92.080