To index properties.

§1.

typedef struct property_indexing_data {
    int include_in_index;  is this property shown in the indexes?
    int indexed_already;  and has it been, thus far in index construction?
} property_indexing_data;

void IXProperties::initialise_pid(property *prn) {
    prn->indexing_data.indexed_already = FALSE;
    prn->indexing_data.include_in_index = TRUE;
}

• The structure property_indexing_data is private to this section.

§2. A property might be missed out of the Index pages for clarity's sake:

int IXProperties::is_shown_in_index?Usage of IXProperties::is_shown_in_index:
Index Extensions - §2.9
Inferences - §2, §3(property *prn) {
    return prn->indexing_data.include_in_index;
}
void IXProperties::dont_show_in_index(property *prn) {
    prn->indexing_data.include_in_index = FALSE;
}

§3. During indexing we try to avoid mentioning properties more than once:

void IXProperties::set_indexed_already_flag?Usage of IXProperties::set_indexed_already_flag:
Inferences - §1, §2(property *prn, int state) {
    prn->indexing_data.indexed_already = state;
}
int IXProperties::get_indexed_already_flag?Usage of IXProperties::get_indexed_already_flag:
Inferences - §2(property *prn) {
    return prn->indexing_data.indexed_already;
}

§4. Who can own a property?

void IXProperties::index_either_or(OUTPUT_STREAM, property *prn) {
    property *neg = EitherOrProperties::get_negation(prn);
    WRITE("either/or property");
    if (Properties::get_permissions(prn)) {
        WRITE(" of "); IXProperties::index_permissions(OUT, prn);
    } else if ((neg) && (Properties::get_permissions(neg))) {
        WRITE(" of "); IXProperties::index_permissions(OUT, neg);
    }
    if (neg) WRITE(", opposite of </i>%+W<i>", neg->name);
}

void IXProperties::index_permissions?Usage of IXProperties::index_permissions:
Instances - §6(OUTPUT_STREAM, property *prn) {
    for (int ac = 0, s = 1; s <= 2; s++) {
        property_permission *pp;
        LOOP_OVER_PERMISSIONS_FOR_PROPERTY(pp, prn) {
            wording W = InferenceSubjects::get_name_text(
                PropertyPermissions::get_subject(pp));
            if (Wordings::nonempty(W)) {
                if (s == 1) ac++;
                else {
                    WRITE("</i>%+W<i>", W);
                    ac--;
                    if (ac == 1) WRITE(" or ");
                    if (ac > 1) WRITE(", ");
                }
            }
        }
    }
}