I have come across an old descendant chart written in French for one of my ancestors. I can decipher the French, what I can't understand is the lines connecting the generations.

There is no vertical line between the earliest ancestor and the second generation. But the lines between the second and third generations and between the third and fourth generations are dashed. But the remaining generations are solid lines.

The second generation doesn't show a marriage, just a mother with the children taking her surname. Neither does the third generation show a marriage. This time it is a male who would have been 57 when his only child (at least the only one listed) was born.

So my theory is the dashed lines represent illegitimate births. Is this a standard symbology?