#### Aux List

NeXtMidas looks for a file by searching a collection of auxiliaries, or the read AUX list. The `AUXILIARY` command establishes NeXtMidas auxiliary disk/path assignments for writing and locating data files. An auxiliary, or aux, may be a directory or a URL; it may be a short string or numbers in string form. In general, NeXtMidas auxes are named, not numbered, and are not restricted to being on the local file system. These features simplify NeXtMidas access to files identified by URL.

`EXPL AUXILIARY` (or `AUX`) provides a list of standard auxiliaries for the NeXtMidas system.

`READ` and `WRITE` are special reserved names which define the list of AUX names currently in use.

There are three special auxiliaries:

- `CWD` - Always points to the current directory and changes as the current directory changes.
HOMEPATH - Points to the current user macro homepath and changes as the homepath changes (see also `EXPLAIN HOMEPATH` from the NeXtMidas command prompt)
- `DAT` - Points to a special global data directory

The <`read aux`> parameters define or alter the path list used to locate Midas data files. The syntax of <`read aux`> is as follows:

- ``n1|n2|n3`` - An ordered search list of one or more aux names separated by vertical bars or as separate arguments.
- ``ALL`` - Defines the read aux list to include all paths in the AUX table except READ, WRITE, CWD, DAT, HOME.
- ``-AUX`` - Removes aux from the current read aux list
- ``+AUX`` - Adds aux to the end of the current read aux list.
- ``AUX+`` - Adds aux to the front of the current read aux list.

When any file is opened, whether for read or write, all disks in the current auxiliary read list are searched. Therefore, the longer the aux list, the longer it takes to open a file, particularly if the aux list includes networked disks. If the application requires reopening a file frequently, try using its full pathname. When the pathname is detected, the aux list is not searched.

Examples:

``AUX`` - Display the current aux settings and associated paths

``AUX 1 ALL`` - Write new files to aux 1 and read from all available disks

``AUX 1 DAT`` - Write to aux 1 and read from aux DAT. A minimal read list reduces search time.

``AUX CWD`` - Write to the current directory (read aux is unchanged)

``AUX ,, -CWD`` - Remove aux CWD from the current read list, write aux unchanged

``AUX ,, +DAT`` - Add aux DAT to the end of the current read list