That line at the top of an Inform source text, saying what it is and who wrote it.

§1. It might seem sensible to parse the opening sentence of the source text, the bibliographic sentence giving title and author, by looking at the result of sentence-breaking: in other words, to wait until the syntax tree for a project has been read in.

But this isn't fast enough, because the sentence also specifies the language of syntax, and we need to know of any non-English choice immediately. So a special hook in the syntax module calls the following function as soon as such a sentence is found; thus, it happens during sentence-breaking, not after it, and may therefore affect how subsequent sentences are broken. 

enum BadTitleSentence_SYNERROR

void BiblioSentence::notify(inform_project *proj, parse_node *PN) {
    wording W = Node::get_text(PN);
    if (<titling-line>(W)) {
        text_stream *T = proj->as_copy->edition->work->title;
        if (proj->as_copy->edition->work->author_name == NULL)
            proj->as_copy->edition->work->author_name = Str::new();
        text_stream *A = proj->as_copy->edition->work->author_name;
        inform_language *L = <<rp>>;
        if (L) {
            Projects::set_language_of_play(proj, L);
            LOG("Language of play: %S\n", L->as_copy->edition->work->title);
        }
        Extract title and author name wording1.2;
        Dequote the title and, perhaps, author name1.3;
    } else {
        copy_error *CE = CopyErrors::new(SYNTAX_CE, BadTitleSentence_SYNERROR);
        CopyErrors::supply_node(CE, PN);
        Copies::attach_error(proj->as_copy, CE);
    }
}

§1.1. This is what the top line of the main source text should look like, if it's to declare the title and author. 

<titling-line> ::=
    <plain-titling-line> ( in <natural-language> ) |  ==> { R[1], RP[2] }
    <plain-titling-line>                              ==> { R[1], NULL }

<plain-titling-line> ::=
    {<quoted-text-without-subs>} by ... |  ==> { TRUE, - }
    {<quoted-text-without-subs>}           ==> { FALSE, - }

§1.2. Extract title and author name wording1.2 = 

    wording TW = GET_RW(<plain-titling-line>, 1);
    wording AW = EMPTY_WORDING;
    if (<<r>>) AW = GET_RW(<plain-titling-line>, 2);
    Str::clear(T);
    WRITE_TO(T, "%+W", TW);
    if (Wordings::nonempty(AW)) {
        Str::clear(A);
        WRITE_TO(A, "%+W", AW);
    }

§1.3. The author is sometimes given outside of quotation marks:

"The Large Scale Structure of Space-Time" by Lindsay Lohan

But not always:

"Greek Rural Postmen and Their Cancellation Numbers" by "will.i.am"

Dequote the title and, perhaps, author name1.3 = 

    Str::trim_white_space(T);
    if ((Str::get_first_char(T) == '\"') && (Str::get_last_char(T) == '\"')) {
        Str::delete_first_character(T);
        Str::delete_last_character(T);
        Str::trim_white_space(T);
    }
    LOG("Title: %S\n", T);
    Str::trim_white_space(A);
    if ((Str::get_first_char(A) == '\"') && (Str::get_last_char(A) == '\"')) {
        Str::delete_first_character(A);
        Str::delete_last_character(A);
        Str::trim_white_space(A);
    }
    if (Str::len(A) > 0) LOG("Author: %S\n", A);