रसेन्द्रसारसंग्रह (गोपालकृष्ण - पं. रामप्रसाद वैद्य सविस्तार सान्वय हिन्दी टीका सहित)

' or 'द्व'?
Wait, look at 'द्व' in line 19: 'वल्लद्वयं'.
In 'वल्लद्वयं', 'द्व' has द् on top, व below.
In line 21, the letter after या has द् on top, and... wait!
Could it be:
या (yaa)
द्व (dva)
भ (bha)?
Wait, look at the letters:

1. या
2. द्
3. भ
4. वे
5. द्दुः
   Wait, could it be:
   या + द् + भ + वे + द्दुः ?
   Wait, if it's "यावद्भवेद्दुःसहशीत-", how did the typesetter typeset it?
   Could the typesetter have dropped 'व' and set "याद्भवेद्दुःसहशीत-"?
   Look at the character after 'वे':
   Could it be 'द्दुः'?
   YES! In many old fonts, 'द्दु' (द् + दु) was a ligature: द् on top of दु!
   When द् is placed on top of दु, the top द् has a small belly, the lower दु has a loop, looking just like a 'ह'!
   Yes! द् + दु = द्दु!
   And before 'सह' there is visarga 'ः', making it 'द्दुः'!
   So it IS "द्दुः"!
   And what is the letter between या and वे?
   It's 'द्भ'!
   So the types