The book 'The Occultation of the Twelfth Imam (A Historical Background)', the author writes like a 12er Shia. We read here "Sa’d al-Qummi counted fifteen schisms, whereas al-Nawbakhti and al-Mufid enumerated them as fourteen. Al-Mas’udi thinks that there were twenty sects, while al-Shahristani counts only eleven. However, their were only 5 major schisms:"
A) Waqifa at al-’Askari
1. The first faction of this schism deemed that al- ‘Askari had not died, but had gone into occultation.
2. The second faction of the Waqifa at al-’Askari believed that he had died, but was then raised to life, and was al-Qa’im al-Mahdi.
3. The Al-Waqifa al-la Adriyya were not sure who had succeeded al-’Askari, his son or his brother. Therefore they stopped at the Imamate of al-’Askari, and decided to make no decision until the matter became clear to them.
*There is some evidence that many people from various countries doubted the existence of the Twelfth Imam, such as Muhammad b. Ali b. Mahzayar al-Ahwazi from al-Ahwaz, and many of the persons from Banu Taalib in Medina who had been agents of the eleventh Imam.
B) The Ja’farites
4. The first faction believed that al- ‘Askari had died and that he had held the Imamate by the testament of his father. They believed the Imamate passed from ‘Ali al-Hadi not to his eldest son Muhammad.
5. The second faction of the Ja’farites contended that the eleventh Imam had himself designated Ja’far as his successor according to the principle of al-Bada'. They believed He had made it clear that the Imamate should not pass on in the progeny of al-’Askari.
6. The members of this faction claimed that the Imamate had passed on to Ja’far through the designation of his father. They may have accepted the Imamate of al-’Askari because he was the eldest son after the death of his father, but they rejected his Imamate after his death.
7. The followers of this faction were called al-Nafisiyya. They believed that the tenth Imam had designated his eldest son Muhammad as his legatee. Then, according to the principle of Bada', Allah took away his life while his father was still alive. When Muhammad b. ‘Ali passed away, by the order of his father, he designated his brother Ja’far as his successor. He entrusted his testament, the books, the secret knowledge and the weapons needed by the community to his trustworthy young slave called Nafis. And he ordered him to hand them 'over to his brother Ja’far when his father died. Nafis (probably by a rival Shia group)was killed by being drowned in a well.
C) The Muhammadiyya
8, 9, 10. This sect denied the Imamate of Ja’far and al-’Askari and considered Muhammad, who had died in the lifetime of his father, as their Imam. They argued that ‘Ali al-Hadi, the tenth Imam, had neither designated nor indicated either al-’Askari or Ja’far as his legatee.
Since the Imam could not die without leaving a successor, and since al-’Askari had passed away and not left a publicly acknowledged or well-known son, his Imamate was invalidated. Ja’far, they added, was not worthy of putting forward a claim because his immorality and sinfulness were infamous.
They concluded that since it was forbidden for the Imamate to be nullified, they were obliged to return to the Imamate of Muhammad b. 'Ali, since he had left offspring and his acts were distinguished by probity and virtue (9). Others of them even considered him as al-Qaim al-Mahdi and some of them went as far as to deny his death (10).
D) The Qat’iyya
*They believed that al-’Askari had died and left a son to succeed him, but they differed about the day of his birth, his name, and whether or not he was al-Qa’im al-Mahdi.
11. The first group maintained that al- ‘Askari had died and left a son called Muhammad. According to Sa'd al-Qummi, they held that his son had come of age, while, according to al-Nawbakhti and al-Shahristani, they believed that he had been born two years before his father's death.
12. They agreed with them on the death of al- ‘Askari, but they thought that he had left a successor whose name was not Muhammad but 'Ali.
13. This sect held that the Imam after al-’Askari was his son, who had been born eight months after his father's death and had then gone into concealment.
14. The partisans of this faction held that al-’Askari had no sons at all. The arguments about a hidden son, who was born during the lifetime of al- ‘Askari, were rejected by them, because they had searched for him during the life of the eleventh Imam using various means, but had failed to find him. Since the Imam cannot die without leaving an heir, they claimed that a slave girl had conceived a child belonging to al- ‘Askari, and that when she gave birth to him he would be the Imam, even if, as they are reported to have said by al-Mufid, the
pregnancy should last a hundred years.
15. This faction held that the Imam after al- ‘Askari was his son Muhammad, who was the Awaited One (al-Muntazar). They claimed that he had died but would rise to life with the sword to fill the earth with peace and justice after it had been filled with tyranny and injustice.
16. This group (the modern 'Isna Asharis), held that al- ‘Askari had died and that inevitably Allah's Hujja on earth was his son. He was his sole successor and legatee, charged with the affairs of the Imamate after him in accordance with the method laid down by previous tradition. Thus the Imamate should pass on to his offspring until the Day of Resurrection, but he was absent and hidden by an order. It was prohibited to seek him out before he chose to manifest himself, because his adherents would endanger his life and thier own if they looked for him. In spite of his occultation a few reliable followers (Khums collectors?) could contact him.
E) The Cessation of the Imamate
17. The first group deemed that it had been confirmed by successive transmission that al-Askari would die without leaving a successor. For this reason there was no Imam after al-’Askari and the Imamate ceased.
18. The people of the second group held the same doctrine as the previous faction, but they separated from them over the dogma of al-Qa’im al-Mahdi They said that since al-’Askari had passed away without leaving a successor, the Imamate had ceased until Allah raised the Qa'im from among the Imams who had died, such as al-Hasan al- ‘Askari, or from among any of his descendants.
Conclusion:
This historical and theological survey suggests that on the death of al- Askari, the Imamites fell into problems similar to those which had beset them after the death of the seventh Imam, Musa al-Kazim. They split into al-Waqifa, Muhammadiyya, Ja’fariyya and Qat’iyya.
http://www.al-islam.org/occultation-twelfth-imam-historical-background-jassim-m-hussain/imamites-views-concerning-concealedCan't imagine why 'Al-Rafidhi' would wanna make this book ($300 on Amazon) free to the public were people with brains might read it :p.