term% ls -F
term% pwd
term% cat index.txt
AS(1)                       General Commands Manual                      AS(1)

       as - assembler

       as [ - ] [ -o objfile ] file ...

       As  assembles  the  concatenation  of the named files.  If the optional
       first argument - is used, all undefined symbols  in  the  assembly  are
       treated as global.

       The  output  of  the  assembly  is left on the file objfile; if that is
       omitted, a.out is used.  It is executable if no errors occurred  during
       the assembly, and if there were no unresolved external references.

       /lib/as2       pass 2 of the assembler
       /tmp/atm[1-3]? temporary
       a.out          object

       ld(1), nm(1), adb(1), a.out(5)
       UNIX Assembler Manual by D. M. Ritchie

       When an input file cannot be read, its name followed by a question mark
       is typed and assembly ceases.  When syntactic or semantic errors occur,
       a  single-character diagnostic is typed out together with the line num‐
       ber and the file name in which it occurred.  Errors  in  pass  1  cause
       cancellation of pass 2.  The possible errors are:

       )  Parentheses error
       ]  Parentheses error
       <  String not terminated properly
       *  Indirection used illegally
       .  Illegal assignment to `.'
       a  Error in address
       b  Branch instruction is odd or too remote
       e  Error in expression
       f  Error in local (`f' or `b') type symbol
       g  Garbage (unknown) character
       i  End of file inside an if
       m  Multiply defined symbol as label
       o  Word quantity assembled at odd address
       p  `.' different in pass 1 and 2
       r  Relocation error
       u  Undefined symbol
       x  Syntax error

       Syntax  errors  can  cause incorrect line numbers in following diagnos‐

                                     PDP11                               AS(1)