data. It provides technology data that can express foundry process design rules through at least 20 nm, contains the definitions of the layers and purposes used in the design, definitions of VIAs and routing rules, definitions of operating points used for analysis, and so on. OA makes extensive use of IC-specific data compression techniques to reduce the memory footprint, to address the size, capacity, and performance problems of previous DBs. Despite what its name could imply, this file format has no publicly accessible implementation or specification. Those are exclusive to the members of the OpenAccess Coalition. Synopsys Milkyway The Milkyway database was originally developed by Avanti Corporation, which has since been acquired by Synopsys. It was first released in 1997. Milkyway is the database underlying most of Synopsys' physical design tools: IC Compiler and Astro physical synthesis Star-RCXT RC parasitic extractor Hercules LVS/DRC physical verification Milkyway stores topological, parasitic and timing data. Having been used to design thousands of chips, Milkyway is very stable and production worthy. Milkyway is known to be written in C. Its internal implementation is not available outside Synopsys, so no comments may be made about the implementation. MDX C-API At the request of large customers such as Texas Instruments, Avanti released the MDX C-API in 1998. This enables the customers' CAD developers to create plugins that add custom functionality to Milkyway tools (chiefly Astro). MDX allows fairly complete access to topological data in Milkyway, but does not support timing or RC parasitic data. MAP-in Program In early 2003, Synopsys (which acquired Avanti) opened Milkyway through the Milkyway Access Program (MAP-In). Any EDA company may become a MAP-in member for free (Synopsys customers must use MDX). Members are provided the means to interface their software to Milkyway using C, Tcl, or Scheme. The Scheme interface is deprecated in favor of TCL. IC Compiler supports only TCL. The MAP-in C-API enables a non-Synopsys application to read and write Milkyway databases. Unlike MDX, MAP-in does not permit the creation of a plugin that can be used from within Synopsys Milkyway tools. MAP-in does not support access to timing or RC parasitic data. MAP-in also lacks direct support of certain geometric objects. MAP-in includes Milkyway Development Environment (MDE). MDE is a GUI application used to develop TCL and Scheme interfaces and diagnose problems. Its major features include: Graphical editor for viewing and editing Milkyway databases TCL command interpreter Scheme