What is the meaning of mahavakya? What was/is it used for, I mean what is its importance? What does mahavakya convey? This is not specifically with respect to Advaita Vedanta, but in general whichever darshana or any school who used that term.
Note: This is not a duplicate of any of the questions linked below.
I am asking the usage of mahavakya in the past by different schools, not Advaita alone.
For eg: Adi Shankaracharya uses mahavakya in a different sense in Sariraka Bhasya 1.3.33:
न हि महावाक्ये ऽर्थप्रत्यायकेऽवान्तरवाक्यस्य पृथक्प्रत्यायकत्वमस्ति यथा न सुरां पिबेत् इति नञ्वति वाक्ये पदत्रयसंबन्धात्सुरापानप्रतिषेध एवैकोऽर्थोऽवगम्यते न पुनः सुरां पिबेदिति पदद्वयसंबन्धात्सुरापानविधिरपीति।
na hi mahāvākye'rthapratyāyake'vāntaravākyasya pṛthakpratyāyakatvamasti yathā na surāṃ pibet iti nañvati vākye padatrayasaṃbandhātsurāpānapratiṣedha evaiko'rtho'vagamyate na punaḥ surāṃ pibediti padadvayasaṃbandhātsurāpānavidhirapīti।
For in general any minor syntactical unity, which is included in a more comprehensive syntactical unity conveying a certain meaning, does not possess the power of expressing a separate meaning of its own. Thus, for instance, we derive, from the combination of the three words constituting the negative sentence, '(Do) not drink wine,' one meaning only, i.e. a prohibition of drinking wine, and do not derive an additional meaning, viz. an order to drink wine, from the combination of the last two words, 'drink wine.'
Here, the mahavakya is "(Do) not drink wine".
Another example, Satya Sai or his disciples used the word mahavakya in another sense: Satya Sai Mahavakyas
Thus, I am asking how mahavakyas have been used by different schools, what is the meaning they want to convey?