explanation about the B2 VISA pfmap2003-11-24 22:07:00

Hi, My parentsjust got their B2 visa in shanghai. I have a question here. According to the following info:

ENYRIES ISSUEDATE EXPIRATION DATE
M 21NOV2003 20MAY2004

Does it mean they can only stay till 20May2004 no matter when they enter into US. I remember the 6months should be counted from the exact date one enter into US?

Thanks

No.

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