Nissan reused chassis code from "5" for brand new car, not continuation? Why?

Nissan chassis code system normally is 1st alphabet and rest of two are numbers.

Example: XYZ

X is alphabet, Y is the car type, Z is the generation.

In the 1970s, every time Nissan changed new generation of the vehicles, Nissan used the chassis code by add 100 as newer generation, but until late 1970s. Example: Nissan Sunny

B10>B110>B210>B310 

While adding 100 for each generation, but +1 was used for emission or updates (facelift). Example: Nissan Urvan.

First generation: E20, but it had E21 and E22 as facelift with improvement of E20. So, second generation was E23.

Now, Nissan reused certain chassis code for its new cars, began from generation "5". Nissan Kicks is an example, using Nissan Primera P-chassis code, P15. Why is P15 on Kicks, not P13 as Primera was only until P12? Actually there is some reasons why Nissan does not use P13 for Kicks, instead P15.

Nissan Primera was European D-segment sedan, produced from 1990 till 2008, carried over three generation, P10, P11 and P12, meanwhile Kicks is B-segment subcompact crossover SUV. If Nissan allocates Kicks as P13, consumers will be confused that Nissan Kicks is succeeded by Primera in terms of chassis code, although they are completely different vehicle segment.

P12: Nissan Primera sedan
P15: Nissan Kicks SUV
<P13, P14 become a gap>

While using recycled chassis code for new models, begins from "5", Nissan actually keeps distance away from their old discontinued models chassis code range. So, P13 and P14 become a gap actually. Other than Kicks, and Primera, here are some examples.

S30/31: Nissan Fairlady Z (Roadster)
S35: Nissan Rouge SUV
<S32, S33, S34 become a gap>

F10/11: Datsun 100A/Cherry (A-segment supermini)
F15: Nissan Juke (B-segment SUV)
<F12, F13, F14 become a gap>

Nissan Lafesta is another different case, its first generation was B30, then second generation (based on Mazda 5) was B35.

In the future, for smaller cars range, Nissan may use these reused chassis code, starts from "15", such as:

- A15 (formerly was Stanza A10/11 where discontinued in 1981)
- C15 (unknown yet. Although Nissan Pulsar C13 was just discontinued in Europe 2 days ago, but Tiida C12 is still on sale in selected Asia countries, it is still unknown that Nissan will launch C14 to replace Tiida and Pulsar hatchback as conventional C-segment hatchback is denied)
- M15 (formerly was Prairie/Liberty M12 where discontinued in 2005)
- R15 (formerly was Presea R11 where discontinued in 2000 under Nissan Revival Plan)
- T15 (formerly was Stanza T12 where discontinued in 1990)
- W15 (formerly was Avenir W11 where discontinued in 2006)
- Z15 (unknown yet. Although Nissan Cube was discontinued for export markets in 2016/17, but it is still on sale in Japan, no replacement for Cube Z12 is announced, Nissan may discontinue Cube in the future)

If the Nissan code generation was only goes up to "0", Nissan can start from "1" for their new vehicles. Example:

C10: Nissan Skyline (compact sports sedan)
C11: Nissan Versa/Tiida/Latio (subcompact sports sedan)

E10: Nissan Cherry (A-segment supermini)
E11: Nissan Note (B-segment mini MPV)

J30: Nissan Maxima (D-segment sedan)
J31: Nissan Teana (D-segment sedan)

A30: Nissan Prince Gloria (executive sedan)  
A31: Nissan Cefiro (D-segment sedan)

- So, Nissan can use V11 for future model?

V10: Nissan Tino (MPV)
V11: future models?