"File types"

[Don]

Chuck Guzis wrote:
> On 8/28/2006 at 4:47 PM Don wrote:
> 
>> No, those are file *permissions*.
> 
> Are you asking, "Did any system keep file type information out of the file
> name?"  The answer is "yes, several did".  Here's part of a microcomputer
> floppy directory from a circa 1977 OS.  Note that fiile dates show this
> disk was probably created around 1986 (yes, it's all in ASCII--no binary
> fields here):
> 
> A$DIRECTORY	000000001500000016	SF 	064032386                       
> ACONFIG.SYS	000160001610000016	DV 	000010199                       
> AMT.PARTS  	000170001702700017	DV 	000010199
> ADX85M26D03	000180004643600046	LV 	000080483
> AISAM.SYS  	000470005814400058	SV 	000080483
> A$AUTOSTART	000620006201300062	PV 	000080483                       
> ARUN       	000630009348700093	SV 	000080483
> AMTMENU    	001120013036800130	OV 	000010199                       
> ALOCATE    	001310014242700142	OV 	000010199                      
> A$SBA.C    	001430014400000143	II 	003               
> A$SBA.C@   	001450014800000145	MF 	055
> 
> First column is the file name, the second is the file allocation and length
> information.  The third column is the file type and the record type.
> S=System D=data,  L=boot loader, P=profile, O=binary object, I=ISAM index,
> M=ISAM data (there are other types).  The second characters is the type of
> record F=fixed, V=variable, I=index.  The fourth column is the record
> length and the creation date.    By convention, ISAM index files take the
> name of the data file, with an "at" sign appended, though there was no
> particular system requirement for this.
> 
> If you enter the name of a file that didn't have the O file type, the
> system won't execute it.  Similarly, you can't open a file with anything
> other than the DV attributes for text display or editing.  ISAM files are
> handled by the ISAM manager and nothing else.  You can't do ANYTHING with S
> or L  type files, not read them, not write them directly.
> 
> I've seen other systems from the 70's with this kind of directory
> information.   However, the idea of a file extension for certain types of
> files was contagious--note the CONFIG.SYS (well in advance of MS-DOS).

Yes, I *know* this has been done other ways in the past.
What I am trying to figure out is the rationale behind
why it has (apparently) migrated into the file *name*.

Valid (though silly!) arguments could include things like:
- portability (file system independance)
- efficiency (no need to have extra atributes *in* the file)
- The Evil Empire couldn't come up with anything more original
- "Just Because"

I.e. if you were starting from scratch *today*, why would
you chose to encode file types in file names?  vs. some
other alternative??