Defines and other are different? why? not understand how work code mod

[Gobbibomb]

Why if i create
01_defines.txt and write
NGameplay = {
#TEST
EMPIRE_SIZE_BASE = 15 # No penalties at this empire size or below #da 30
EMPIRE_SIZE_FROM_DISTRICTS = 1 # Per district #da 1
EMPIRE_SIZE_FROM_SYSTEMS = 1 # Per system
EMPIRE_SIZE_FROM_COLONIES = 30 # Per planet # da 5
EMPIRE_SIZE_FROM_BRANCH_OFFICES = 2 # Per branch office
EMPIRE_SIZE_FROM_POPS = 1 # Per pop #da 0.5
}
this work
but if i create
01_ship_sizes.txt
and write
corvette = {
resources = {

category = ships
cost ={
alloys = 500
}
}

}

not work? why?

 

[mial42]

Paradox scripting language is inconsistent and poorly documented. Defines let you change individual defines within a block without overwriting the entire block (ie, defines you don't explicitly change aren't affected). In most other folders, like ship_sizes, if you include an object like corvette, you're overwriting the entire object, not just the lines within it you change (meaning that the new corvette object you've created completely replaces the old one; meaning that it needs to include everything necessary to the corvette, not just the things you want to change).
Some folders require you to overwrite the entire file, rather than let you overwrite individual objects within it.

The stellaris modding wiki has information about different folder's overwrite types, but not all of it seems to be correct (modding jobs, for instance, require overwriting the entire job file rather than the individual job).