500702 Portugieser Automatic Case Markings

I just came into possesion of a new Portguieser Automatic in Rose Gold.  

I'm curious about the markings on the case.  They lie directly beneath the straps and are visible if the watch is viewed from the side.  

On the bottom of the watch are two markings.  One appears to say 750 in between two scales and the marking to the left of it is a complete mystery.  I had to take a picture of it with a digital camera to be able to even discern what the markings are.  From the naked eye they look like ugly misprints on the side of the watch.  

At the top of the watch there are very clear markings that say IWC and AU 750.

Are the markings on the bottom of the timepiece a mistake or are they supposed to be there? 

Everything else is so perfectly done that it just doesn't seem fitting to have these markings that look like flaws on the case.  

I can upload pictures if necessary.

AU750 means 18K Gold, ie 75% pure gold. 
You are describing the gold case hallmark stamps. 

As others are pointing out the two hallmarks are:  One representing the gold content.  750 means 18k gold.  The other is the Head of a St. Bernard. It apprears on Swiss Made watches.

Thanks Bill!  Thats definitley it. 

I dont think I would have ever guessed that it was a dogs head but now its so obvious. 

Now that I know what to search for I noticed this was discussed back in 2013 for any casing that has precious metal.  Just an FYI it looks like the sub marking in the St .Bernard is a letter Z.

The Z refers to the Canton of Zürich.  It should be on the dog's ear.  Schaffhausen is the Capitol of Schaffhsuen Kenton, but the Hallmarks may be controlled out of Zürich.  Someone else may have better info.