Types of instruction manuals

Question

I noticed there are 4 different types of instruction manuals (at least for large sets):

• Type I: Similar piece colors are not very distinguishable (especially Dark Gray and Black). Some building steps could be clearer (for example, adding arrows or changing the point of view). Similar-looking pieces are sorted in the same bag. Bags are not numbered.
• Type II: Same as Type I but with numbered bags.
• Type III: The piece colors are a lot closer to the actual pieces and are easily recognizable (Black has even a white outline). All building steps are better described. Pieces are better sorted in the bags. Bags are numbered.
• Type IV: Same as Type III but with the pieces to be added in a given step outlined in yellow or red.

One could think of a type to be an improvement over the previous one, and when a new type is released, the old one wouldn't be used anymore. But that's not the case.

Here are some sets with their corresponding type:

• Mobile Crane (8421) released on 24-Oct-07 is of Type II.
• Death Star (10188) released on 21-Jun-08 is of Type I.
• Pet Shop (10218) released on 12-May-11 is of Type II.
• Town Hall (10224) released on 03-Mar-12 is of Type IV.
• Palace Cinema (10232) released on 01-Mar-13 is of Type III.
• Mobile Crane MK II (42009) released on 27-Jul-13 is of Type II.
• Maersk Line Triple-E (10241) released on 01-Jan-14 is of Type IV.
• Parisian Restaurant (10243) released on 01-Jan-14 is of Type III.

Do you know why the manual types are not in strict chronological order?

Answer 1

I remember that in the 80's black technic parts where always hard to recognize in the instructions, in those years you had to count the studs yourself. Over the years black became a little lighter in colour to a dark grey. This was also shown on one of the first pages of the instructions.

This stays OK until the introduction of dark grey parts. At that point LEGO struggled again with colours in the instruction. This was around 2008. In the year later this was solved by making black darker again. This current colour scheme is used in for example 42009. So this set is not a type II but another type. Also LEGO nowdays try to keep the same parts both in black and dark grey to a minimum per set.

Until now I never noticed that LEGO uses two different ways to show black parts. With and without a white outline. And also on the PDF's instruction it look like the shade of black is different. I don't know the reason for this and if the white outline is only used for non technic sets.

Numbered bags are used through the whole line of sets. And make the building a little easier by reducing the number of parts to look through while finding the part needed.

The coloured outline on the build steps are used at least from 2000. These are often used in larger models like 3723-1: LEGO Mini-Figure, where it can be hard to see where a part go. Often because of the uniform colour of a model.

Answer 2

I would hypothesize that, perhaps, it's not a matter of one style being the "official" current style at a given time so much as there are probably multiple individuals or teams that write the manuals for assembling the models, each of whom have a slightly different writing and illustration style.