I am learning SED, but I dont know this script

I had searched in manual, what 's mean "The first 20 entity skills can be set in WED's entity properties panel" ? So what do skill use for ?? thanks reply.

The "skills" are a set of 100 VARs that are "attached" to EACH entity as properties.
So each entity has its own "local" set of values for you to store things in, like health, armour, ammo, etc
To access those values you reference them like entity_name.skill5 etc.
If it is an action, say assigned in WED, you would use my.skill5 etc.
Do you follow me?

From within the WED editor, it only lets you access to the first 20 of these skills.

Now, access the skills by using skill1, skill24, etc is cumbersome, so you can use "defines" to relabel them
for easier accessing. Lite-C defines and C-Script defines work the same but have a slightly different syntax.
Check the manual. (The define you have shown is a lite-c define)

The define tells the compiler "every time I see argument1, replace it with argument2".
So if you have #define health skill1 then everytime you use "health" in your source code,
then the compiler will replace it with "skill1".For example my.health will be compiled as my.skill1.
Much easier to read.

Hope this helps clear things up.

Ok, I had seen how to use skills, But I don't still see
Is it alway skill1:health, skill2:armor, skill3:ammo? So if I have a bullet entity, Is it still skill1:health,skill2:armor ? Is it default ?? . Thanks reply.

No its the way you want it to be.
As EvilSOB explained, the #define just lets you write a name instead of skillX (x begin a number from 1 to 100)

You can undefine a label for a skill if you want to and redefine another label.
Example:
You have a movement.c file which labels skill1 as health
and you have a weapon.c file which labels skill1 as damage

Of course there are certain scripts around which use the skills based up on the programmers choice.

If you
#define skill1 healt
then skill1 is the healt

and if you
#define skill1 armor
then skill1 is the armor

Have a look at the manual "#define" and "skill"

I'll rephrase this a little.
The "define" allows to to assign ADDITIONAL names to a skill. Think of it as a "nickname".

EG
#define health skill5
#define damage skill5
From here on in, if you change/read my.health you are changing/reading my.skill5,
AND if you change/read my.damage you are ALSO changing/reading my.skill5.
The 'define's are not linked to any specific entity.
So if you only use my.health with a player or enemy entity, then skill5 is its health.
And if you only use my.damage with bullet-type entities, then skill5 is how much damage it does.
ALSO you can CONTINUE using "skill5" as its name if you want, if the entity is not a player, enemy, or bullet.

Ok i see, thanks very much. I love u ^_^