Is Sitemap complemental or main?

I forget to add old indexed link to sitemap, will it disappear from Google?

[net_rambler]

Hello!

Is sitemap complemental service or main?

What will happen to my old link, which I forgot to add to sitemap? It has good position in SERPs...

Do I need to update my sitemap or should think that this is suplemental service for Google which gives more knowledge to bot to extend search area, not to limit...

we have have robots.txt which restricts indexing area...

Am I right?

Do we need sitemaps only to inform Google about pages that are probably not found by bot, or we actually define important spots on our sites and say:
this well indexed link is not important anymore that's why I have not included it into sitemap, decrease its rank...

!
I do not want it, I want just to extend index area, not decrease it :-)!

Please answer my question, guys...

[abates]

So long as there are links to the page, Google will index it, whether it's in your sitemap or not...