Dear Karman ,
If you are talking about Engineering as procurement and shop drawing :
1- Material procurement : direct cost for the material its self and any other cost related to bring the material to the site , transportation , custom clearance and so on will be indirect cost for the activity.
2- Shop drawing work : shop drawing work could be direct cost of all the project , you collect the technical office salaries for all the project and it will be direct cost over the project direct cost.
But in our case we did not talk about any actual cost we talking about budget cost or we can rename it as selling price cost for the items and it refers to the money we will get for the client by doing the activity as it is in the specification with its quantity.