I agree with the author of SRFI 97 that the "R6RS is
broken in that it doesn't support a natural indexing
of perhaps the largest widely supported set of Scheme
libraries."  I also agree with him that the burden of
justifying that R6RS restriction on library names
rests with advocates of the R6RS.

That burden has been met by two lead implementors of
R6RS-compatible systems (out of, by my count, a grand
total of four lead implementors) saying they will not
implement the natural extension that would allow the
R6RS to coexist with long-established SRFI policies
and practice.

Turning to workarounds, Roman numerals and the prefix
#\n have been suggested.  Here are more suggestions,
all of them R6RS-conforming, and all written as
alternative names for SRFI 6:

    (srfi :6)
    (srfi /6)
    (srfi *6)
    (srfi =6)
    (srfi <6>)
    (srfi ?6)
    (srfi _6)
    (srfi ~6)
    (srfi ->6)

I vote for (srfi :6).  My second choice is (srfi ->6).

Hope that helps.

Will