C-XSC. A programming environment for verified scientific computing and numerical data processing. C-XSC is a tool for the development of numerical algorithms delivering highly accurate and automatically verified results. It provides a large number of predefined numerical data types and operators. These types are implemented as C++ classes. Thus, C-XSC allows high-level programming of numerical applications in C and C++. The C-XSC package is available for all computers with a C++ compiler translating the AT&T language standard 2.0.