As lithographic requirements drive minimum feature dimensions into the 0.5-micron range, the use of conventional optical tools gives way to other, less conventional methods during the pattern processing. The most serious contenders in a production environment are high-throughput, E-beam, direct-write tools. These systems can generate features as small as 0.25 μm, but cannot yet match the throughput of optical equipment. A method of achieving submicron patterning is to use E-beam direct-write lithography for critical levels of the fabrication and optical lithography for the remainder. For this strategy to work, the ability of the various tools to overlay correctly is required. AEBLE 150 is designed not only to meet such requirements but, of equal importance, to facilitate the use of such strategy. The ability of this system to modify the placement of geometries in real time is the basis by which overlay with other equipment can be achieved. This requires characterizing the previous level or levels by measuring some sort of reference marks. The challenges present in the implementation of such a scheme are the ability to match the various distortion characteristics of the optical tools being used, to acquire a variety of pre-existing alignment marks, and to acquire these marks under non-optimal conditions due to previous processing steps. Finally, for a production system, this must be accomplished using methods that will not compromise its throughput or ease of use. This paper covers the design philosophy and implementation of the system to allow interfacing to other tools; the user's perspective from the definition of alignment mark types, structure and their location in the substrate; and finally the results achieved with a test that simulates matching a distorted wafer.