HPlogo Accessing Files Programmer's Guide: HP 3000 MPE/iX Computer Systems > Chapter 2 Creating A File

Summary of Overrides

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If a FILE command has been entered that contradicts some of the HPFOPEN/FOPEN parameters for a file, which takes precedence? What happens if some parameters are left out? The file system maintains a hierarchy of overrides for just such situations (illustrated in Figure 2-1 “File System Hierarchy of Overrides”):

Figure 2-1 File System Hierarchy of Overrides

[File System Hierarchy of Overrides]

Since the physical characteristics of a file cannot be changed after it has been created, it makes sense that the file label would take precedence over all commands. Other determinants are effective only when a new file is being created.

NOTE: FILE commands and HPFOPEN/FOPEN calls cannot alter physical characteristics of an existing file.