प्रगृह्य-सन्धि - 1

The प्रगृह्य-सन्धि includes all exceptions of the types of स्वर-सन्धि where the सन्धि does not take place. The cases where the सन्धि is optional are NOT included in प्रगृह्य-सन्धि. These exceptions are called as प्रगृह्य Exceptions. The respective exceptions of all the previously mentioned सन्धिs are given there itself for ease of understanding. 
Note: Though "प्रगृह्य-सन्धि" is mentioned, NO सन्धि takes place in this type.