There is an annoying profusion of ways an action can have a name.

§1. An action_name can be referred to in quite a number of ways, and the rules about that are gathered into this structure:

typedef struct action_naming_data {
    struct noun *as_noun;  such as "taking action"
    struct wording present_name;  such as "dropping" or "removing it from"
    struct wording past_name;  such as "dropped" or "removed it from"
    int it_optional;  noun optional when describing the second noun?
    int abbreviable;  preposition optional after the first noun, if there's no second?
} action_naming_data;

• The structure action_naming_data is accessed in 4/anaa, 4/anl, 4/nap and here.

§2. Here, the default settings are made from W. The past tense form is made automatically from the present. The noun form is made using the following construction; thus, the run-time value corresponding to "taking" is "the taking action".

<action-name-construction> ::=
    ... action

• This is Preform grammar, not regular C code.

§3.

void ActionNameNames::baptise?Usage of ActionNameNames::baptise:
Actions - §2(action_name *an, wording W) {
    an->naming_data.present_name = W;
    an->naming_data.past_name =
        PastParticiples::pasturise_wording(an->naming_data.present_name);
    an->naming_data.it_optional = TRUE;
    an->naming_data.abbreviable = FALSE;
    word_assemblage wa = PreformUtilities::merge(<action-name-construction>, 0,
        WordAssemblages::from_wording(W));
    wording AW = WordAssemblages::to_wording(&wa);
    an->naming_data.as_noun = Nouns::new_proper_noun(AW, NEUTER_GENDER, ADD_TO_LEXICON_NTOPT,
        MISCELLANEOUS_MC, ARvalues::from_action_name(an), Task::language_of_syntax());
    Vocabulary::set_flags(Lexer::word(Wordings::first_wn(W)), ACTION_PARTICIPLE_MC);
    action_name *an2;
    LOOP_OVER(an2, action_name)
        if (an != an2)
            if (ActionNameNames::action_names_overlap(an, an2)) {
                an->naming_data.it_optional = FALSE;
                an2->naming_data.it_optional = FALSE;
            }
    ActionsPlugin::notice_new_action_name(an);
}

§4. In the early days of Inform, past participles had to be set explicitly, and we retain the ability for authors to do that; but the automatics are now good enough that this is almost never used.

void ActionNameNames::set_irregular_past?Usage of ActionNameNames::set_irregular_past:
Actions Plugin - §10.3(action_name *an, wording C) {
    if (Wordings::length(C) != 1)
        StandardProblems::sentence_problem(Task::syntax_tree(),
            _p_(PM_MultiwordPastParticiple),
            "a past participle must be given as a single word",
            "even if the action name itself is longer than that. (For instance, "
            "the action name 'hanging around until' should have past participle "
            "given just as 'hung'; I can already deduce the rest.)");
    wording W = an_being_parsed->naming_data.past_name;
    feed_t id = Feeds::begin();
    Feeds::feed_wording(C);
    if (Wordings::length(W) > 1) Feeds::feed_wording(Wordings::trim_first_word(W));
    an_being_parsed->naming_data.past_name = Feeds::end(id);
}

§5. We are unlikely to need other tenses.

wording ActionNameNames::tensed?Usage of ActionNameNames::tensed:
§10, §11, §13
Actions Plugin - §4
Actions-Only Nodes and Annotations - §3
Actions - §3
Action Semantics - §5.1
Action Name Lists - §27, §34.1.2
Going - §3(action_name *an, int tense) {
    if (tense == IS_TENSE) return an->naming_data.present_name;
    if (tense == HASBEEN_TENSE) return an->naming_data.past_name;
    internal_error("action tense unsupported");
    return an->naming_data.present_name;
}

void ActionNameNames::log?Usage of ActionNameNames::log:
IF Module - §2, §2.3(action_name *an) {
    if (an == NULL) LOG("<null-action-name>");
    else LOG("%W", ActionNameNames::tensed(an, IS_TENSE));
}

§6. Object pronouns — let's just say, the word "it" for brevity — in an action name are significant: they are placeholders for where the first of two nouns is supposed to go. Thus, in the action name "unlocking it with", the word "it" shows where to put the name of what is being unlocked.

In an "abbreviable" action name, the preposition after the "it" can be omitted in source text: thus "unlocking it" would do as well as "unlocking it with".

And even the "it" can be omitted, taking us right down to "unlocking", but only if there is not ambiguity in doing so. We became more careful about this when an author innocently created different actions called "pointing at" and "pointing it at" in the same work: the trouble being that "pointing" might be a legal abbreviation for both of them. The following looks for action names which overlap in this way, so that permission to lose the "it" can be withdrawn in their cases:

int ActionNameNames::action_names_overlap?Usage of ActionNameNames::action_names_overlap:
§3(action_name *an1, action_name *an2) {
    wording W = an1->naming_data.present_name;
    wording XW = an2->naming_data.present_name;
    for (int i = Wordings::first_wn(W), j = Wordings::first_wn(XW);
        (i <= Wordings::last_wn(W)) && (j <= Wordings::last_wn(XW));
        i++, j++) {
        if ((<object-pronoun>(Wordings::one_word(i))) && (compare_words(i+1, j))) return TRUE;
        if ((<object-pronoun>(Wordings::one_word(j))) && (compare_words(j+1, i))) return TRUE;
        if (compare_words(i, j) == FALSE) return FALSE;
    }
    return FALSE;
}

§7. The "non-it length" of an action name is the number of words other than the pronoun. For example, the non-it length of "unlocking it with" is 2.

int ActionNameNames::non_it_length?Usage of ActionNameNames::non_it_length:
Action Name Lists - §8(action_name *an) {
    int s = 0;
    LOOP_THROUGH_WORDING(k, an->naming_data.present_name)
        if (!(<object-pronoun>(Wordings::one_word(k))))
            s++;
    return s;
}

§8. Whether "it" is optional is determined automatically, then, but whether the preposition can be abbreviated is under the author's control:

int ActionNameNames::it_optional?Usage of ActionNameNames::it_optional:
Action Name Lists - §34.1.2(action_name *an) {
    return an->naming_data.it_optional;
}

void ActionNameNames::make_abbreviable?Usage of ActionNameNames::make_abbreviable:
Actions Plugin - §10.2(action_name *an) {
    an->naming_data.abbreviable = TRUE;
}

int ActionNameNames::abbreviable?Usage of ActionNameNames::abbreviable:
Action Name Lists - §34.1.2(action_name *an) {
    return an->naming_data.abbreviable;
}

§9. The names of the three rulebooks associated with an action are built here. Note that it is absolutely required that the names consist of a fixed prefix wording, followed by the present-tense name of the action in question.

<action-rulebook-construction> ::=
    check ... |
    carry out ... |
    report ...

• This is Preform grammar, not regular C code.

§10.

wording ActionNameNames::rulebook_name?Usage of ActionNameNames::rulebook_name:
Actions - §3(action_name *an, int RB) {
    int N = 0;
    switch (RB) {
        case CHECK_RB_HL:     N = 0; break;
        case CARRY_OUT_RB_HL: N = 1; break;
        case REPORT_RB_HL:    N = 2; break;
        default: internal_error("unimplemented action rulebook");
    }
    word_assemblage wa = PreformUtilities::merge(<action-rulebook-construction>, N,
        WordAssemblages::from_wording(ActionNameNames::tensed(an, IS_TENSE)));
    return WordAssemblages::to_wording(&wa);
}

§11. Parsing descriptions of action is in general very difficult, but here are some simple starts in on it.

The following matches an action name with no substitution of noun phrases, and without the word "action": thus "unlocking it with" matches, but not "unlocking the door with" or "unlocking it with action".

This should be used only where speed is unimportant. It would not be a good idea to use this when parsing action patterns.

<action-name> internal {
    action_name *an;
    LOOP_OVER(an, action_name)
        if (Wordings::match(W, ActionNameNames::tensed(an, IS_TENSE))) {
            ==> { -, an };
            return TRUE;
        }
    LOOP_OVER(an, action_name)
        if (<action-optional-trailing-prepositions>(ActionNameNames::tensed(an, IS_TENSE))) {
            wording SHW = GET_RW(<action-optional-trailing-prepositions>, 1);
            if (Wordings::match(W, SHW)) {
                ==> { -, an };
                return TRUE;
            }
        }
    ==> { fail nonterminal };
}

• This is Preform grammar, not regular C code.

§12. However, <action-name> can also be made to match an action name without a final preposition, if that preposition is on the following list. For example, it allows "listening" to match the listening to action; this is needed because of the almost unique status of "listening" in having an optional noun. (Unabbreviated action names always win if there's an ambiguity here: i.e., if there is a second action called just "listening", then that's what "listening" will match.)

<action-optional-trailing-prepositions> ::=
    ... to

• This is Preform grammar, not regular C code.

§13. The following returns the longest-named action beginning with the wording W and which cannot take nouns; and the word number posn is moved past this number of words.

action_name *ActionNameNames::longest_nounless?Usage of ActionNameNames::longest_nounless:
Actions - §5(wording W, int tense, int *posn) {
    action_name *an;
    LOOP_OVER(an, action_name)
        if (ActionSemantics::can_have_noun(an) == FALSE) {
            wording AW = ActionNameNames::tensed(an, tense);
            if (Wordings::starts_with(W, AW)) {
                if (posn) *posn = Wordings::first_wn(W) + Wordings::length(AW);
                return an;
            }
        }
    return NULL;
}