

What youre doing is a really poor and crippling way of trying to learn openings.
It would appear to be, but I'm fascinated by the ECO for its own sake. The above, to me, is a kind of Rosetta stone that could make it clear how to look at the data.
My curiosity is legitimately piqued. Do you actually know the answer to the question? Do you know what the through line is between all those different representations of the data?
The ECO system is a unified partition of all openings in 500 classes A00 to E99.
Before the ECO system people gave openings names, sometimes ambiguous, sometimes different in different languages, sometimes long.
Petrov = Russian = C42 and C43 (Steinitz Variation)
Spanish = Ruy Lopez = C6 - C9
Italian = Giuoco Piano = C5
Berlin Defence = C67
Marshall Attack = C89
The ECO is uniform, independent of language, short, unambiguous
Well A00, for instance, is basically 1.g3 and 1.b4, and it makes it clear that the former is preferred. So if that's the one ECO code for irregular openings, then one big question becomes, how many irregular openings are being listed in front of me? Are they just going to limit themselves to the two that are worth playing? Does that mean I'm looking at the Hungarian and the Polish as definitions, or as suggested lines?
Also: the fact that each entry is put together as a game, does that mean it should be viewed in terms of an actual game, or is it simply a compact way of structuring a database, and it shouldn't be interpreted except as lines separated from each other?
#7
"A00, for instance, is basically 1.g3 and 1.b4" ++ No, A00 is everything else but A01 to E99.
"it makes it clear that the former is preferred" ++ ECO is a labeling system, it expresses no preference.
"how many irregular openings are being listed in front of me?" ++ All 14 of them.
"Are they just going to limit themselves to the two that are worth playing?" ++ No.
"Does that mean I'm looking at the Hungarian and the Polish as definitions, or as suggested lines?" ++ No, neither definition, nor suggested. A00 is defined as everything but 1 b3, 1 f4, 1 Nf3, 1 c4, 1 d4, 1 e4. Hence it contains 1 a4, 1 a3, 1 b4, 1 c3, 1 d3, 1 e3, 1 f3, 1 g3, 1 g4, 1 h3, 1 h4, 1 Na3, 1 Nc3, 1 Nh3. Of those 1 b4 or 1 g3 are most played.
#8
"does that mean it should be viewed in terms of an actual game"
++ No, not really. The move sequence given is one way to reach the position
"simply a compact way of structuring a database" ++ Yes, giving a possible move order is more compact and understandable than giving a diagram or a FEN.
"it shouldn't be interpreted except as lines separated from each other?" ++ Yes.
This insight is really invaluable. Thank you. I think figuring out how to separate it into lines will be the next part of the task. I can see the lines in ChessBase Reader, though they range from a few moves to more than 20. What's so interesting to me is that it doesn't seem to exist as separated lines, outside of a table. It seems to exist in every *other* way.
Well A00, for instance, is basically 1.g3 and 1.b4, and it makes it clear that the former is preferred. So if that's the one ECO code for irregular openings, then one big question becomes, how many irregular openings are being listed in front of me? Are they just going to limit themselves to the two that are worth playing? Does that mean I'm looking at the Hungarian and the Polish as definitions, or as suggested lines?
Actually, what you say is wrong. A00 is not "g3 and b4".
It is ALL OTHER FIRST MOVES besides 1.b3, 1.f4, 1.Nf3, 1.c4, 1.d4, and 1.e4.
How much coverage each gets depends on which edition of ECO you are looking at (condensed versions will likely only mention g3 and b4).
For example, 1.Nc3 also falls under A00 if it does not transpose somewhere else. 1 Nc3 d5 2.e4 is B01. 1.Nc3 Nf6 2.d4 d5 is D01. 1.Nc3 Nf6 2.g4 is A00. 1.Nc3 Nf6 2.e4 is B02.
Do not get tied up with ECO codes as transpositions often occur.
1.e4 d5 (B01 - Scandinavian) 2.exd5 Nf6 3.c4 c6 4.d4 cxd5 (Oops, now it is B14 - Caro-Kann Panov-Botvinnik Attack) 5.Nc3 e6 6.Nf3 Bb4 7.Bd3 dxc4 8.Bxc4 and I cannot recall if it is 8...cxd4 9.exd4 b6 or 8...O-O 9.O-O b6 that now makes it E53 (Nimzo-Indian).
The fact that you have a condensed version already is misleading you into thinking that A00 specifically means 1.g3 or 1.b4 when that is false. If you played a game right now with 1.a4, it would be classified as A00.