I have a line chart series that is for accounting. A sample query would pull back 12 rows (1 row for each month, Jan - December), and the columns would show the dollar amounts for separate buckets of money allocations. What I'm trying to do is have the series chart line start @ 0 (we're trying to mimic another chart that does the same thing).
Resolution was reached with the help of a "Periods" look-up table that I created.
My main table, which showed the 12 monthly periods, had one column which was a long date-time field. I took that and got the monthname().
With this new look-up child table, I defined an int column ("PKID") from 0-12 (...yes, 13 values/rows) to get the ordering I wanted along with a second column of the month name. For int values 0 and 1, I applied this to the first month, so for January, I had two rows.
For my series lines, I had to do an expression that said if the int value of PKID in the look-up table was 0, then the value for the line was 0...hence, I got the lines to start at x,y of 0.
From the customers point of view, the January series line looked like it started from 01/31 in the beginning when the report was first developed w/o this PKID field...and they wanted it to really start @ 01/01. For the category (horizontal) axis, I made sure to turn the label off if PKID = 0.