The regulations for procurement of services relating to the investigations, research and excavation Article 5

If there is doubt about inviting a specific supplier, an Agency may publish a notice of invitation to solicit suppliers publicly for price competition or price negotiation on the Government Procurement e-Bidding System of Public Construction Commission, Executive Yuan, the Government Procurement Gazette or make it available on the information network. For tendering procedures, an Agency shall prescribe a reasonable time-limit for tendering from the date of publishing a notice.
中文原文 考古遺址調查研究發掘採購辦法第5條
邀請特定廠商有疑慮者,得採公告方式,於行政院公共工程委員會採購資訊公告系統、政府採購公報或辦理採購機關之資訊網路公開徵求供應廠商,作為邀請比價或議價之用;公告等標期,由機關視需要合理訂定。

English translation for reference only; the Chinese text prevails. Not legal advice.