HP OpenVMS Systems Documentation

The read and write attributes subfunctions are used for operations suchas reading and writing file protection and creating and revising dates.A read or write attributes operation is invoked by specifying anattribute list with the QIO parameter P5. A read attributes operationcan be invoked by the major I/O function IO$_ACCESS (see Section 1.6.2);a write attributes operation can be invoked by the major I/O functionsIO$_CREATE, IO$_DEACCESS, and IO$_MODIFY (see Sections 1.6.1,1.6.3, and 1.6.4).

1.3.5.1 Input Parameters

The read or write attributes subfunction is controlled by theattribute list specified by P5. The list consists of a variable numberof two longword control blocks, terminated by a 0 longword, as shown inFigure 1-6. The maximum number of attribute control blocks in onelist is 30. Table 1-6 describes the attribute control block fields.

Figure 1-6 Attribute Control Block Format

Table 1-7 lists the valid attributes for ACP-QIO functions. Themaximum size (in bytes) is determined by the required attributeconfiguration. For example, the Radix-50 file name (ATR$S_FILNAM) usesonly 6 bytes, but it is always accompanied by the file type and fileversion, so a total of 10 bytes is required. Each attribute has twonames: one for the code (for example, ATR$C_UCHAR) and one for the size(for example, ATR$S_UCHAR).

Table 1-8 lists the bits contained in the file characteristicslongword, which is read with the ATR$C_UCHAR attribute.

Figure 1-7 shows the format of the record attributes area.

Figure 1-7 ACP-QIO Record Attributes Area

Table 1-9 lists the record attributes values and their meanings.