The convention used in the diagram I linked to is an abreviated diagram, but it is consistent and complete.

Essentially, each junction between line segments and each unconnected endpoint of a line segment represents a carbon at that position unless otherwise illustrated; further, the appropriate number of hydrogens are assumed to be joined to any carbon such that all four bonding slots of the carbon are completed (unless otherwise illustrated).

So, for example, the carbon between the two oxygens which are attached to the phenol ring is implied by the fact that two line segments join at that point; further, the two hydrogens necessary to fill the bonding slots of that carbon are implied by the lack of any other notation to the contrary. (Each carbon has four possible bonding slots; the carbon connecting the two oxygens has two slots occupied by the connection to the two oxygens, and two filled by hydrogens.)

In addition, the presence of the methyl group is implied by the fact that there is a line segment with one endpoint dangling without connection to another line segment; also, the three hydrogens necessary to fulfill that carbon (and thus form the methyl group) are therefore also implied by the convention as mentioned above.

Another possible point of confusion is that the MDMA depicted in "my" diagram seems to be a chiral racemate of the version shown in PIHKAL...

I like to think of this diagram as elegant; but I understand if other people consider it, uh, confusing at best

. I apologize if I made it any more unclear than it had to be; it's just that good chemical diagrams (and which are in the public domain) are so gosh-darned hard to come by these days... lol