Analysis
By Zaffar Abbas BBC correspondent in Islamabad

Pakistan's 342-member National Assembly has a very different complexion from three years ago, when it last met.

Most familiar political figures are missing because of the laws that barred them from contesting the October general election.

Fazlur Rahman (left): "Democratic mullah"

A new law had made it mandatory for candidates to have college degrees and, as a result, there are many new and young faces.

Because of the re-introduction of reserved seats for women, there are also more than 70 women MPs, compared to just a couple in the two previous assemblies.

Perhaps more significant is the dominating presence of the alliance of religious parties, the Muttahida Majlis-e-Amal (MMA), who have 66 representatives in the house.

They are led by Maulana Fazlur Rahman, known abroad as a conservative Islamic leader whose party supported Afghanistan's Taleban movement.

At home, he has the reputation of a "democratic mullah" who worked with former premier Benazir Bhutto's government and has remained at the forefront of campaigns against military rule since the 1970s.

Constitution row

President Pervez Musharraf's wish that parliament accept the sweeping constitutional changes he has made has sparked a bitter debate among the newly-elected MPs.

Pro-Musharraf politicians won the most votes

Many of them insist on taking the oath of office under the provisions of the 1973 constitution, so heavily amended by President Musharraf.

"Rules of business" and tradition lay down that the chief election commissioner (CEC) preside over the inaugural session and administer the oath to the new MPs under that constitution.

Conscious of the controversies surrounding this transition, and allegations of rigging in the October polls, CEC Irshad Hasan Khan excused himself from presiding over the inaugural session of this assembly.

Flexibility needed

But the debate on the status of Pakistan's constitution is far from over.

Musharraf: Changed the constitution

President Musharraf insists that the changes he has introduced, through what is known as the Legal Framework Order (LFO), are now part of the constitution.

The newly-elected MPs are divided on the issue, with anti-Musharraf groups swearing to abide by the 1973 constitution unchanged by a military ruler.

However, politicians from across the divide are not willing to describe this as a crisis that cannot be resolved.

Many of them believe that - with some flexibility shown by General Musharraf and his opponents - an agreement can be reached on a trouble-free session and power can be transferred to an elected parliament.