a new type of device is to useH one of the undefined bits in the F.RCTL field (bits 6 and 7) andA set the remaining bits as appropriate for the new device.l 4.2.2 File AccessH The next category of FCS modules are the various OPENH routines. FCS supports three methods of opening files: normal,H filename block, and file-ID. The first form calls the parsingH routines to setup the filename block and then opens theH specified device/file. The filename block version assumes theH parsing routines have already been called. The final form usesH information from a previous file access to directly open the HACP/TASK INTERFACE PAGE 4-5+ file. No parsing logic is invoked.sH Adding a new ACP merely involves dispatching at theH appropriate point in the OPEN logic to perform any I/O requiredH by the ACP to establish an I/O process. The new logic isH responsible for returning the appropriate information to theH FDB, particularly the file-attribute section (F.RTYP, F.RATT,H F.RSIZ, F.HIBK, F.EFBK, and F.FFBY). These fields are used byH FCS to determine how records should be processed, when newH blocks need to be allocated to the file, and where the logicalH EOF is positioned. For Files-11, these fields are stored in theH file header. FCS retrieves them when an existing file is openedA and stores the current FDB values when a file is created.eH Unless the new type of device supports some unique fileH identifier, the open by file-ID mechanism will either have to beH emulated by the ACP or made illegal.