Tmost important member of any terror module is the bomb-maker.
He usually stays some place else, comes to a targeted city like Mumbai to assemble the devices and returns to his base the morning before or a day before the acts of terrorism happen.
He is much too valuable to the terrorists. Bomb making is only known to a few people and the terrorists cannot afford to lose him, which is why they protect him the most.
The bomb-maker may or may not be known to other members of the module. If they know them, they would almost certainly not know his real name.
Looking at the photographs of the damaged train compartments in last Tuesday's blasts I believe RDX was not used. RDX in a closed environment like a train compartment could have caused many more casualties. The impact of the blast would have been considerably higher.
Gelatin sticks were used in the 2002-2003 blasts in Mumbai. They were sourced from a quarry in Hyderabad. In those cases, three to five kilos of gelatin sticks were covered with clothes, food and other things and put in duffel bags and left on buses and trains. Gelatin sticks are easily available and can cause the kind of damage that one saw last Tuesday.
The handler is the individual who runs the terror module. In most cases he is a Pakistani. He coordinates everything -- from deciding which group will carry out the act of terror to determining the targets. It has to be a small group. It cannot be 25 people, which increases the possibility of the plot being leaked out.
The handler could be a member of an organisation like the Lashkar-e-Tayiba or Jaish-e-Mohammad. He is in constant touch with his bosses in Pakistan. Members of the module may only know him under an assumed name.
The handler usually stays in a city different from the one that is being targeted. In the 2003 blasts in Mumbai, the city police discovered that the handler was based in Pune for three months and made two or three trips to Mumbai every month. He had been in India for three years, posing as a salesman and living in cities like Bangalore, Chennai and Coimbatore.
The July 11 blasts were the first serial explosions in Mumbai since the ten bomb blasts of March 12, 1993. There have been other blasts since then, but they were not executed in such a precise manner. This module appears well coordinated. They must have conducted dry runs and on the day itself they must have moved the bags in quickly.
If we are lucky we won't have another incident within the next month. The terrorists have been unsuccessful in their objective of provoking communal riots in Mumbai. So they will try again and see if they succeed the next time. But no crime is perfect. These terrorists should remember that.