Marking Pens and dvd's (safety?) — DVD Tech — DVD MP3 AVI MP4 players codecs conversion help

Warning: filemtime() [function.filemtime]: stat failed for /etc/webs/russian.html in /home/webs/media.mst.com.ua/ngadmin/includes/Smarty/Smarty.class.php on line 1598

Warning: Smarty error: unable to read resource: "/etc/webs/russian.html" in /home/webs/media.mst.com.ua/ngadmin/includes/Smarty/Smarty.class.php on line 1143

Warning: filemtime() [function.filemtime]: stat failed for /etc/webs/russian.html in /home/webs/media.mst.com.ua/ngadmin/includes/Smarty/Smarty.class.php on line 1598

Warning: Smarty error: unable to read resource: "/etc/webs/russian.html" in /home/webs/media.mst.com.ua/ngadmin/includes/Smarty/Smarty.class.php on line 1143

A while back sharpie came out with pens that are safe for dvd's/cd's.
It was found that some media was going bad after some time from the ink.
Unfortuneately, sharpie only comes in 4 colors for the cd/dvd safe pens.
I noticed that "bic" now has them in acid free ink. The company could
not tell me if they were safe or not.
So what is the deal? Is the main thing to be "acid free"? Or is there
an abrasiveness factor too?
Are the bic "markit" acid free ones safe?
TIA. mes.