Japanese to English Bus/Financial Law: Contract(s)

In the phrase: X社が、民法上で規定される契約行為（請負または準委任契約）により、Y社に注文してからY社内でプロジェクトが開始される。
I found the term "turn-key contract" for 請負契約, which seems correct since the latter is for a finished good. In the same place I also found the term "fixed-price" for 準委任契約. However, I didn't find anything about price when researching 準委任契約 in Japanese, so I'm not sure "fixed-price contract" is the best rendering of it.
Thanks for your help!

my references:
http://ci.nii.ac.jp/naid/110003726340/en/

http://www.banzaicopyright.com/documents/ukeoi_inin_2009.pdf