Open bidding，also called open calls for tenders，or advertid tenders，are open to all vendors or tractors who bsp;guarantee performance，while lected bidding，whibsp;is limited petitive bidding，also called restricted tenders，restricted calls for tenders，or invited tenders，are only open to lected prequalified vendors or tractors，and it may be a two-stage process，of whibsp;the first stage produbsp;a short list of suitable vendors and then the d stage is for the suitable vendors to pete for bidding.
（2）iated Bidding
iated Bidding is a non-petitive bidding.It is only open to a few particular tractors for ion for a deal.In this method the pribsp;to be paid for the work is iated with a single tractor.This，obviously，does not provide the owner with a parative price.The cost of a work may be higher in this method，but the owner expebsp;some advantages from employing a particular tractor who policies and practibsp;are known and who has in the past proved capable of fulfilling his obligations.The higher cost may be offt by better quality.
Open bidding，also called open calls for tenders，or advertid tenders，are open to all vendors or tractors who bsp;guarantee performance，while lected bidding，whibsp;is limited petitive bidding，also called restricted tenders，restricted calls for tenders，or invited tenders，are only open to lected prequalified vendors or tractors，and it may be a two-stage process，of whibsp;the first stage produbsp;a short list of suitable vendors and then the d stage is for the suitable vendors to pete for bidding.
（2）iated Bidding
iated Bidding is a non-petitive bidding.It is only open to a few particular tractors for ion for a deal.In this method the pribsp;to be paid for the work is iated with a single tractor.This，obviously，does not provide the owner with a parative price.The cost of a work may be higher in this method，but the owner expebsp;some advantages from employing a particular tractor who policies and practibsp;are known and who has in the past proved capable of fulfilling his obligations.The higher cost may be offt by better quality.
（3）Two-stage Bidding
This is a mixed method of unlimited petitive bidding and limited petitive bidding，in whibsp;the open bidding is first offered and then the lected bidding method is ud in two-stage process.