continuation....

When to Start and Stop Fasting
(38) Once the entire disk of the sun has disappeared [below the horizon], the fasting person should break his fast and not pay any attention to the red glow that remains on the horizon. The Prophet (?) said:
"Once night comes from there and the day disappears from there, and the sun has set, the fasting person should break his fast."
The Sunnah is to hasten in breaking the fast. The Prophet (?) would not pray Maghrib until he had broken his fast, if only with a sip of water.If a fasting person cannot find anything with which to break his fast, he should have the intention in his heart to break his fast and should not suck his finger [or the like], as some of the common folk do. He should beware of breaking the fast before the correct time. Once the Prophet (?) saw some people hanging from their hamstrings with blood pouring from the corners of their mouths. When he asked about them, he was told that they were people who broke their fast before it was time to do so.If a person is certain, thinks it most likely, or is in equal doubt whether or not he broke the fast before the proper time, he should make up the fast later on, for the basic principle is that the day has not ended.  He should beware of relying on the word of small children or untrustworthy sources, and he should also beware of the time differences between different cities and villages when he hears the adhaan on the radio and so on.
(39) When dawn appears, which is the white light which spreads across the horizon in the East [well before the actual sunrise], the fasting person must stop eating and drinking straightaway whether he hears the adhaan or not. If he knows that the mu`edhin calls the adhaan at dawn, he has to stop eating and drinking as soon as he hears his adhaan, but if the mu`edhin calls the adhaan before Fajr, he does not have to stop eating and drinking when he hears it. If he does not know the mu`edhin's usual practice, or there are differences among the mu`edhins and he is unable to determine the time of dawn for himself - as is usually the case in cities due to lighting and buildings - he should take the precaution of referring to a printed timetable, so long as he is sure that the calculations on which it is based are not incorrect.
The idea of taking precautionary measures by stopping eating and drinking a certain time before Fajr, such as ten minutes before, is bid'ah.
On some timetables you can see one heading for "imsaak" (stopping eating and drinking) and another for Fajr. This is something that is contrary to Islam.
(40) The Muslims living in cities where there is a distinct alternation of night and day in every twenty-four hour period are obliged to fast, no matter how long the day is, so long as there is a distinction between night and day. In those places where there is no such distinction, Muslims should fast according to the times in the nearest city in which there is a distinct alternation of night and day.