REVMEDIA FKB Articles - AREV, OI, REV G, jREV, JCDC, LIVEWATER,ADVANCED REVELATION, OPENINSIGHT, REVELATION G

RevMedia FKB

Document	V2I8A1
Title	Reader's Clinic - Volume Pointer Record
Keywords	VOLUME W559 POINTER RTP49 MFS BFS
Text	A reader writes "I've been USING the tips FROM the December issue of REVMEDIA on creating Volume file VARIABLES and I keep getting a W559 error message" ﾚﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄｿｳ Cannot continue ｳｳ An attempt was made to execute a null ("") program ｳｳ Press any key to contine ｳﾀﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾄﾙ This problem occurs when the Volume pointer in Voc is modified to establish Volume MFSs (It is possible to have an MFS apply to every file on a volume by inserting the MFS name before the BFS name (@VM delimited) in the Volume pointer ) When this happens the structure of the volume file variable changes slightly In this case the @VMs in the Filing System list must be converted to @SVMs Thus the code given on page 11 of issue 7 would be modified to be FS = VOL_REC<4> DOS = VOL_REC<5> CONVERT @VM TO @SVM IN FS FILE_VAR = FS : @VM : DOS Alternatively if the Volume has not been attached another way of getting all of the information required to create a volume file variable is to make a DIRECT call to RTP49 (the routine used by the V18 ATTACH processor) This is a subroutine taking four parameters (A B C D) where A is the volume name B is a flag (set to 0) C is the Volume Record returned and D is the Volume Pointer Record returned C has five fields the fifth of which is the Map file variable D has three fields the second of which is the FS list Thus CALL RTP49(A B C D) DOS = C<5> FS = D<2> CONVERT @VM TO @SVM IN FS FILE_VAR = FS : @VM : DOS (Volume 2 Issue 8 Page 3)

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