6 months visitor visa question

[winmunim]

my parents got single entry visitor visa between 9feb2010 and 8august2010. When they arrived at calgary airport, the officer only stamp the passport for the date of entry (24feb2010). no permit or any other papers given by the officer.
How do they know for how long they can stay?
their 6 months starts from the day they arrive?
or do they have to leave the country before 8august 2010? (as their return ticket is on 19 august2010)

If they are not allowed to stay after 8august and if they still stay untill 19th of august, what can happen?!
they are from india, so arrival on mumbai airport while returning back, can the officer give them a trouble for over stay in canada?


thanks you

[job_seeker]

my parents got single entry visitor visa between 9feb2010 and 8august2010. When they arrived at calgary airport, the officer only stamp the passport for the date of entry (24feb2010). no permit or any other papers given by the officer.
How do they know for how long they can stay?
their 6 months starts from the day they arrive?
or do they have to leave the country before 8august 2010? (as their return ticket is on 19 august2010)

If they are not allowed to stay after 8august and if they still stay untill 19th of august, what can happen?!
they are from india, so arrival on mumbai airport while returning back, can the officer give them a trouble for over stay in canada?


thanks you

Yes, their 6 months starts from the date written on their passports.