What is [R=301,NC]?

[fr600]

A line in one of my htaccess is:

RewriteRule ^images.html /index.html [R=301,NC]

It redirects images.html to index.html.

My questions are:

What is [R=301,NC]? What does it do? How is it related to search engines?

Please tell me. Reply briefly if you want. Thanks.

[scrupul0us]

R=301 mean redirect 301 errors (page moved permanently).. the NC im not sure

[goldbug]

The NC stands for 'no case', aka the pattern is case-insensitive.

[fr600]

Thanks for the reply. I have 1 more question atm.

I've redirected all old pages to index.html like:

RewriteRule ^images.html /index.html [R=301,NC]
RewriteRule ^images2.html /index.html [R=301,NC]
RewriteRule ^images3.html /index.html [R=301,NC]
...etc

In this case, search engines possibly won't index all index.html seperately. Only 1 will be indexed and others will be removed from search result, isn't it?