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I am trying to understand the difference between the valid-invalid bit and the modify bit in paging

My current understanding is that the valid invalid bit is in the page table and indicates whether that page has a corresponding frame mapped to it in physical memory. On the other hand the modify bit is present in the frame table which indicates whether that frame has been written into so we can preferably overwrite a frame without having to write it back to disk.

Is this a correct understanding? Particularly the locations where these are present?

Any other insights are gladly accepted

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Image result for page map table entries

This is the structure of page map table, Along with frame's address in which page is residing, it contains a number of information fields like dirty bit, present/absent bit

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Both valid-invalid bit and the modify bit / Dirty Bit are stored in a page table  .

A dirty bit or modified bit is a bit that is associated with a block of computer memory and indicates whether or not the corresponding block of memory has been modified

Most machines keep dirty bits in page table entry .

See this pdf 

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Valid and Invalid present in the page table of concern process and it indicate whether address generated by cpu is valid or invalid.Whereas dirty bit say whether concern page is modified or not in block or particular frame of main memory so that it can be reflected into secondary disk also otherwise new page will overwrite it.

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