SAS Companion for the OS/390 Environment

How SAS Determines Device Types

A fileref has a device type of either MVS or HFS, where HFS identifies files that are stored in the hierarchical file system of UNIX System Services. The device type determines how SAS will access the file. This device type is somtimes referred to as an access method.

If a physical name does not contain a slash (/) or a tilde (~) character to identify it as an HFS filename, SAS uses the following algorithm to determine device type:

Use the HFS access method from the allocation statement, if provided, as in:
```
FILE 'example' HFS;
```
or
```
FILENAME XXX HFS 'example';
```
If the access method is not specified, use the MVS access method.
Use the access method specified by the MVS: or HFS: prefix in the physical filename, if one is provided, as in:
```
FILENAME XXX 'HFS:first';
```
Use the HFS access method if a slash character ( / ) or tilde character (~) appears in the physical filename, as in:
```
FILENAME XXX '~/first';
```
Use the access method specified by the FILESYSTEM= system option. See FILESYSTEM=.

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