public static MetaStackElement parseFromString(LuckPermsPlugin plugin, String s) {
        s = s.toLowerCase(Locale.ROOT);

        // static
        if (s.equals("highest")) return HIGHEST;
        if (s.equals("lowest")) return LOWEST;
        if (s.equals("highest_own")) return HIGHEST_OWN;
        if (s.equals("lowest_own")) return LOWEST_OWN;
        if (s.equals("highest_inherited")) return HIGHEST_INHERITED;
        if (s.equals("lowest_inherited")) return LOWEST_INHERITED;

        // dynamic
        String p;
        if ((p = parseParam(s, "highest_on_track_")) != null) return highestFromGroupOnTrack(plugin, p);
        if ((p = parseParam(s, "lowest_on_track_")) != null) return lowestFromGroupOnTrack(plugin, p);
        if ((p = parseParam(s, "highest_not_on_track_")) != null) return highestNotFromGroupOnTrack(plugin, p);
        if ((p = parseParam(s, "lowest_not_on_track_")) != null) return lowestNotFromGroupOnTrack(plugin, p);
        if ((p = parseParam(s, "highest_from_group_")) != null) return highestFromGroup(p);
        if ((p = parseParam(s, "lowest_from_group_")) != null) return lowestFromGroup(p);
        if ((p = parseParam(s, "highest_not_from_group_")) != null) return highestNotFromGroup(p);
        if ((p = parseParam(s, "lowest_not_from_group_")) != null) return lowestNotFromGroup(p);

        return null;
    }
Contains the standard {@link MetaStackElement}s provided by LuckPerms.
common/src/main/java/me/lucko/luckperms/common/cacheddata/metastack/StandardStackElements.java