Same can't be said of its OS rivals...A consulting group that scrutinises the source code underlying several operating systems has found that a key networking component of Linux is of higher quality in many regards than competing closed-source software. Reasoning, which sells automated software inspection services, examined part of the code of Linux and five operating systems, comparing the number and rate of programming defects. Specifically, Reasoning examined the implementation of TCP/IP, a key networking technology, and found fewer errors in Linux. Reasoning declined to disclose which operating systems it compared with Linux, but said two of the three general-purpose operating systems were versions of Unix. The comparison was done with version 2.4.19 of the Linux kernel. For the comparison products, the company had access to the source code that for proprietary software normally is a closely guarded secret. The company said in its report: "The open-source implementation of TCP/IP in the Linux kernel clearly exhibits a higher code quality than commercial implementations in general-purpose operating systems." Reasoning also compared the code with that used in two special-purpose networking products and found it superior to one of them. Source code is the collection of instructions written by people and later translated into "binaries" that computers can understand. Companies such as Oracle and Microsoft typically sell binaries incomprehensible to humans rather than the comparatively understandable source code. The Linux defect rate was 0.1 defects per 1,000 lines of code, Reasoning found. The rate for the general-purpose operating systems - two of them versions of Unix - was between 0.6 and 0.7 per 1,000 lines of code. The rates for the two embedded operating systems were 0.1 and 0.3 per 1,000 lines of code.