If you don't know the answer, you're not alone.
Most users think little about it unless problems occur.
This turns out to be quite convenient, because it allows Windows to extend the SFT by adding extra blocks. By default, individual applications are limited to 15 open files, but a simple function call removes this limitation. A header at the beginning of each block contains the address of the next one. Running multiple DOS applications in a multitasking environment such as Windows frequently exacerbates the problem. If several applications have files open concurrently, the SFT must be large enough to accommodate them all.