Pillars is something that should be done in starting a job, get along disina means the principal part as reading the Al Fatihah in prayer a central part. Strictly speaking prayer without reciting surat Al-Fatiha is invalid. So pray to the Al Fatihah are inseparable.
Requirement is something that must be kept before mengarjakan something. If the conditions are not perfect something, then the job is not valid.
Legitimate means sufficient condition rukunnya and correct.
Clear rukunya requirement means not enough, or not true. So if any work or cases that do not qualify rukunnya means the case is not valid, or considered a failure.