Yes, the atstrings feature is turned off by default in Arc 3.1 (and also in Anarki's official/stable branches). I think I'll turn off the default in Anarki as well, and just let news.arc continue to make use of it.
Edit 1 hour later: This is now done. Turns out Anarki never meant to turn on atstrings by default. This was a side effect of loading news.arc by default (mea culpa). I've changed things so we load news.arc by default but only use atstrings in news.arc by default. Keep an eye out for subtle bugs introduced by atstrings being turned off when functions in news.arc are called. If we see any I'll probably take out the ability to turn it on and off and just decide to keep it everywhere or take it out entirely.
I don't know if I'd ever want to use this 2D syntax directly, but I'll probably "use" it as a thought experiment for non-hierarchical syntaxes, along with cellular automata and spreadsheets. :)
Can you imagine an 'unquote-splicing operation for this tabuleau syntax? Between lists, 'unquote-splicing can insert any list into any other, but the cells of these tables have externally imposed sizes and shapes, so for an 'unquote-splicing in a table (if we wanted one at all), we'd probably want to enforce that the sizes and shapes match up in a way that makes sense. What might make more sense is to do 'unquote-splicing in a full row or column at once, because at least we get one dimension of freedom that way. If the splice takes up a full row, then it can splice in any number of rows (of any height) to that location.
I'm probably a little obsessed with quasiquotation lately. I've been trying to write an implementation of a macro system where the meanings of notations like 'unquote, 'unquote-splicing, and parentheses themselves can be treated as user-defined macros, and where syntax-bound concepts like source locations and syntax highlighting are mostly managed automatically in the macroexpander rather than something every macro must deal with (except for the macros that do something unusual with them).
Welcome back, conanite! I was coincidentally just thinking about you yesterday when I ran across your bug report at http://arclanguage.org/item?id=10485. Too bad that bug is still open in both Arc 3.1 and Anarki. I think I will try to fix it now that I've spotted it.
I guess the quote idea came from me thinking that the strings were being evaluated. My untrained mind thought "strings evaluate to themselves", but apparently not. So I used the single quote to prevent evaluation.