In this section:
The ClearWin+ interface may be used at three levels:
At the first and simplest level, DOS programs that interact with the user via standard Fortran input and output statements (for example READ, WRITE and PRINT) may be recompiled to produce simple Windows applications with little or no modification to the source code. ClearWin+ will automatically create a window (called a ClearWin window) complete with scroll bars and manage it for the developer.
At an intermediate level, ClearWin+ can be used to provide a professional graphics interface, without incurring the burden of directly using the full Windows API. In particular, the WINIO@ function can be used to produce one or more fully featured GUI windows (called format windows) both quickly and easily. This function dispenses with the need to provide detailed resource scripts for menus, dialog boxes, etc.. It also largely eliminates the requirement for the user to provide complex call-back functions in order to control the interface. The effect is that much of the complexity of using the full API becomes transparent to the programmer. At this level, Windows API functions are rarely needed.
Finally at the lowest level, it is possible for the developer to use ClearWin+ to write programs that use Windows API functions. However, even those who are familiar with the Windows API will probably find it quicker and easier to work at the intermediate level using the ClearWin+ library.
A convention has been adopted in this guide of using mixed case names for the routines present in the Windows API (for example, CreateWindow, GetDC, GetTextMetrics). Routines in the ClearWin+ library do not use mixed case names.