Why cant I use include structure in type or data declaration?

[Former Member]

I just read in one of the SAP standards documents that we should avoid using

Incorrect:

Data: BEGIN OF S_MATERIAL.

INCLUDE STRUCTURE MARA.

Data: END OF S_MATERIAL.

Instead the recommended option is as follows

Recommended:

DATA: S_MATERIAL TYPE MARA. Even if the structure has other components, it can be written as

Data: BEGIN OF S_MATERIAL,

ZMARA TYPE MARA,

S_AFSMAT TYPE J_3AMAD,

component2,

END OF S_MATERIAL.

Why is it so? Can anybody please explain?

Thanks for reading.

[Former Member]

Data: BEGIN OF S_MATERIAL.

INCLUDE STRUCTURE MARA.

Data: END OF S_MATERIAL.

Answer: Dumps you whole structure of MARA in your program.

Recommended:

DATA: S_MATERIAL TYPE MARA. Even if the structure has other components, it can be written as

Answer: References the whole MARA structure during run mode and good for performance.