Not sure how to add a photo but I am reading bhante sujato’s therigatha and in 2.7 mittā it says she kept the eight factored uposatha on 8th, 14th, 15th and “fortnightly special displays”
I have heard some theories on what this might be but would like more insight
I will let more knowledgeable people answer to your main question, but please find here how to upload a photo: by using the “up arrow” button, as showed below.
Hope it helps.
If we get the help of commentary, it seems mean the days before and after the above mentioned uposatha days. That means, 7th-9th and 13th-16th days where we need to enter and exit from sila-observance.
Pali term is “Patihariya pakkham.”
General meaning of “Patihariya” is “a miracle; an extraordinary event.”
But here commentary says it is to be taken as " Pariharaṇa" which means “keeping on; protection; attention.” or as “pariharitabba” which means “should be kept up; should be protected; should be carried about; should be avoided”.
pāṭihāriyapakkhañcā ti pariharaṇakapakkhañca cātuddasīpañcadasīaṭṭhamīnaṃ yathākkamaṃ ādito antato vā pavesaniggamavasena uposathasīlassa pariharitabbapakkhañca terasīpāṭipadasattamīnavamīsu cāti attho.