Referring to previous records in an adaptor

I have an annoying little problem. I have a set of similar-but-slightly-different CSV files (from a spreadsheet) I want to merge into a single file.

I'm a new user, so be gentle with me

There's a date field. Unfortunately, because the person who created the original data thought visually instead of in data terms, the date of the next record, if the same, will be represented with a ditto (") sign instead of the date. So the data looks something like 
and so on.

Is there a heater that can hold the content of the previous record's date field and replace a ditto, if found, with that, and then update the variable and continue? So I'd end up with 
 

Hi Tim,

Yes of course For this you need the LastValue Heater . But your case is a bit tricky because the LastValue Heater only works with empty data fields. The sign “ must be removed before.
To do this you need the a IF-THEN-ELSE condition to check whether the field contains the sign. Only in case “NO” the field content is passed to the LastValue Heater .
If made a brief example, please have a look to the attachment.

Oh, brilliant -- thanks so much, that looks perfect!