Guidance on planning and design of DC links terminating at AC system locations having low short-circuit capacities relative to the DC power infeed. The Guide is limited to those aspects of interactions between AC and DC systems which result from the fact that the AC system is 'weak' compared to the power of the DC link (i.e. AC system appears as a high impedance at the AC/DC interface bus). Some more general aspects of the design and planning of HVDC transmission schemes are described only when this adds to the understanding of the interaction phenomena and for the sake of completeness of the guidelines.