In the Catholic Church this succession is understood to be carried through the sacrament of Holy Orders through the episcopal ordinaries, the bishops.
The Church holds that all bishops have the inherent ability to ordain a baptized male to be a deacon, priest, or bishop.
A valid but illicit ordination, as the name suggests, is one where a bishop uses his valid ability to ordain someone, whom under canon law or instruction from the Pope he was prohibited from ordaining, it therefore being illicit.
However such an ordination / consecration is only valid if properly performed. as in the case of ICAB, their is distinctive detail paid to the fullness of the ordination / consecration and the rites.
In the case of ordination, this is the laying of hands and the proper charge to priesthood.
Another interesting note that the rightful claim of Apostolic Succession of all ICAB Churches stakes its claim on succession though the Diocesan Bishop of Carlos Duarte Costa. Bishop of Botcatu, who had a falling out with Rome.
The ordinations of Bishop Carlos Duarte Costa are seen by the Roman Catholic Church as valid but illicit.
Therefore, any bishop consecrated by Bishop Carlos Duarte Costa or his successors consecrated are valid but illicit, ordination in his turn perform ordinations.
A married man can be validly ordained, except a woman, as women can not hold the office of the priesthood or episcopate, and indeed there are married male priests in both the Orthodox and Roman Catholic Churches.
The confirmation of validity of the church lays down for a valid episcopal consecration is simple. Other than a validly consecrated bishop to perform the rite and a validly ordained priest, who intends to receive consecration, there are just THREE ingredients essential for validity:
1. The imposition of hands by the consecrating bishop (technically called the matter of the sacrament)
2. The essential sixteen word formula recited by the consecrating bishop ( technically called the form of the sacrament).
3. A minimal intention on the consecrating bishop's part "to do what the Church does" (called ministerial intention). Though all the ceremonies prescribed in the rite should be observed, the three foregoing elements are all that is required for an episcopal consecration to be valid.
Comparison Chart of Rebiba Apostolic Succession 
