Awkward to Columnar - Filling a column values relatively placed in another column

Hi all,

I've got source data that comes in the following format:

           ID      XXXX

Date1 Val 1 Val 2 Val 3 Val 4 Val 5

Date2 Val 1 Val 2 Val 3 Val 4 Val 5

Date3 Val 1 Val 2 Val 3 Val 4 Val 5

           ID      YYYY

Date1 Val 1 Val 2 Val 3 Val 4 Val 5

Date2 Val 1 Val 2 Val 3 Val 4 Val 5

Date3 Val 1 Val 2 Val 3 Val 4 Val 5

          ID      ZZZZ

Date1 Val 1 Val 2 Val 3 Val 4 Val 5

Date2 Val 1 Val 2 Val 3 Val 4 Val 5

Date3 Val 1 Val 2 Val 3 Val 4 Val 5

And so on.

I want to transform this data into a continuous table in the following form:

ID      Date   

XXXX Date1 Val 1 Val 2 Val 3

XXXX Date2 Val 1 Val 2 Val 3

          ...

ID      Date   

YYYY Date1 Val 1 Val 2 Val 3

YYYY Date2 Val 1 Val 2 Val 3

So on. 

Or, ideally, fully columnar, like so:

ID      Date   Data

XXXX Date1 Val 1

XXXX Date 1 Val 2

XXXX Date 2 Val 1

XXXX Date 2 Val 2

YYYY Date 1 Val1

YYYY Date 2 Val 2

And so on.

The stage I'm stuck on is dynamically labelling up all of the rows that belong to a certain ID.

My table currently looks like this:

Index Modulo IDCol Date     Valu1 Valu2

1         1          XXXX 

2         2          0         Date 1  Val 1  Val 2

3         3          0         Date 2  Val 1  Val 2

4         1          YYYY

5         2          0         Date1  Val 1  Val 2

6         3          0         Date2  Val 1  Val 2

...

I was able to pull across the ID from the awkwardly placed column above the values into an ID column of its own using a conditional column, but I'm not sure how to fill down the correct IDs (replacing the 0s) for all consecutive dates until the days or the modulo counter resets.

Could anyone help?
Let me know if I need to provide more detail.