The paper considers the influence of design dimension chains on the assembly sequence of a complex product. When assembling products, the rule of connectivity of the dimension chain must be followed. For this reason, the dimension chain induces a binary partial order relation on the set of product parts. The assembly sequences for which the connectivity rule is applied are linear extensions of this order relation. The number of the linear extensions for the orders generated by the main methods of dimensioning is calculated. It is shown that the chain method of dimensioning is the most rigid, and the coordinate method is the most “tolerant”. The combined method occupies an intermediate position. The principle of matching the dimension and mechanical structures of a complex product is proposed. The results obtained can be used to generate rational dimension schemes in integrated CAD / CAM systems.