System file attribute by default is set by operating system or some other program to mark files that are essentially important for proper functioning of system. In MS DOS environment files with system attribute must remain unmodified in their place on disk (not only in virtual folder structure) since boot sequence is started from a fixed location on bootable media. System attribute is usually used jointly with hidden and read only attributes to provide maximum protection of system files. System attribute is usually regarded by programs as a mandatory rule which forbids any actions to be taken upon files or folders marked with this attribute.
Febooti fileTweak utility due to its professional orientation allows to set or clear the system attribute of a file or folder, however this has to be done with maximum caution and awareness since in some occasions it may lead to complete system failure.