While using the MS-DOS DIR command, which of the following switches is not supported in classic DOS 6.x for listing files?

Introduction / Context:
MS-DOS and later Windows command interpreters share many switches, but some options were introduced after DOS 6.x. Identifying which switch belongs to later command processors (like Windows 95/98 or NT) prevents confusion when writing portable batch files for pure DOS environments.

Given Data / Assumptions:

• We are considering classic MS-DOS 6.x behavior.
• DIR switches under review: /P, /W, /S, /T.
• Goal: find the one not supported in DOS 6.x.

Concept / Approach:

In MS-DOS 6.x: /P paginates one screen at a time; /W provides wide columns; /S recurses subdirectories. The /T switch, which selects which time field to display (creation, last access, last write), is a later addition primarily seen in Windows 95/98 DOS sessions and Windows NT/2000's CMD. Therefore, /T is the option not supported in classic DOS 6.x DIR.

Step-by-Step Solution:

Verification / Alternative check:

On a DOS 6.22 system, DIR /? will list supported switches and omit /T, while Windows 9x/NT command prompts document /T with sub-options (C, A, W).

Why Other Options Are Wrong:

• /P: supported; pauses per screen.
• /W: supported; wide listing.
• /S: supported; recursive listing.
• None of the above: incorrect because one unsupported switch exists (/T).

Common Pitfalls:

• Assuming Windows CMD switches work in pure DOS batch scripts.
• Porting scripts between environments without checking DIR /? on the target OS.

Final Answer:

/T.