Would someone please set me straight? I am getting very confused by couple terms that are being used here and elsewhere.

1. What is a princepost?

Neither the TFGuild Glossary nor Websters has a definition for a "princepost" yet it is referred to in "Kingpost Truss Engineering, An Addendum by Ed Levin. September 2004, Timber Framing No. 73." In his assessment of the truss found at Castleton

2. What is a Queenpost?

I was of the understanding according to the TFGuild Glossary that a Queenpost design utilized only two posts which are joined in the center with an anchorbeam. It does not indicate the presence of a Kingpost or that it can be merely a supplement to a kingpost truss. However, Steve Chappell's "A Timberframer's Workshop" 1998 ed. clearly shows on page 109 a king post truss and "Queen posts can be added to the lower third point of the rafters to the tie beam for additional stiffness on longer spans."
How do these differ from princeposts?
Is it a difference in function? (ie. tension rather than compression)
Is it the absence or presence of an additional strut?

3. Do queenposts act in tension or compression?

4. Am I being too picky about definitions and is it acceptable to use these terms interchangeably?

I have seen websites commponly refer to what is clearly a kingpost truss with stuts as a queenpost truss.

I'll help with prince post. It's usually added to a king post truss to provide extra support for the bottom chord (tie beam). It's a vertical member, in tension, hung from the connection between the top of the strut and the rafter. The other end connects to the bottom chord.

The main classroom buildings at North House Folk School, in Grand Marais, MN, use these trusses. They were built in the 30's as part of the WPA, I beleive, as USFS buildings. Sorry for the lousy photo, but it's all I could find on short notice:

Notice taht both the kings and princes are steel rods in this example - clearly that would only work if they were tension members.

I think the main reason they used them in this building was to use the attic for storage. The added weight on the tie beams that hold up the bottom chord required additional support.

I've seen the term queen post applied pretty loosely in a lot of different situations. I do so myself

I call this a queen post bent:

But it's clearly not a truss at all.

Did that help, or just make things worse? CB.

I'm thinking this is a queenpost truss, though the queens are not vertical... from the Carpenter's Fellowship gallery:

My feeling on this subject and I have no basis to base this on is that when a king post is present they are called prince posts, and when no king post is present they are called queen posts....

I've just reviewed the glossary of term in Cecil A. Hewett's "English Historic Carpentry" and he doesn't list prince post in the list of posts depicted in the book.

I've just reviewed the book "Timber Buildings in Britain" by R.W. Brunskill and he lists a princess post as a post between the queen post and the eave of a queen post truss....

Maybe it is this reasoning that makes me think a king post has a prince post as a queen post has a princess post.....

The posts that Mark shows could be called "canted" queen posts...

I Belive the members in Marks post are "canted" struts as they are perpendicular to the rafters.

Is that a truss?

without looking up definitions, I think of a truss as a frame that spans wall to wall and does not add roof thrust to the wall, only weight... so generally a truss has a continuous bottom chord.

I think of a truss as a frame that transmits loads axially among its members. The queenposts in theis truss simply transfer compression loads to the bottom chord and put it into bending. I might be wrong but I would call that a braced rafter.

Take away the queenposts and I'd have a tough time with my definition though, is it a tied rafter or a truss?

I like Diaku's insight as to the compression/tension function of the member. It makes sense to me that a Princepost paired with a Kingpost is acting in tension, supporting the tiebeam from the rafter rather than in compression supporting rafter from the tiebeam. In this way it is a sort of "Mini-Kingpost" when paired with struts.

The Queenpost still is vague as to definition although the definition for Princesses post would place it in compression mode. This would make logical sense and clearly define queen post from kingpost on a functionality basis.

I guess it also makes a difference whether it is a true "truss" configuration vs. merely a bent. Unless I am mistaken bending is not allowed by truss definition, all member must be in either compression or tension. We know this is only theoretical as "sag" can be seen an many historical truss examples. So both Mark and Don P. are right? Over time the compression load of a queenpost truss could cause bending in the lower chord (tiebeam) if severe enough this would result in thrust at the wall plates?

Quuenpost = compression
Kingpost = tension

Queenpost weight is born primarily by bottom chord (tie-beam)
Kingpost weight is born primarily by top chords (rafters)

prince and princess replicate parent of same sex? Is this good logic?