The numbers are the Mac notation of the filepath: The first number (-1 in the example) is the drive ID (the volume on your disk), the second number (e.g. 173584) is the directory ID (the folder in the volume). The two IDs and the file name together form the pathname. If both numbers are 0, or if there are no numbers, Poser uses the text included in the filename as pathname, for example

textureMap 'myDisk:myFolder:M2HeadM2.jpg'
0 0

Poser for Mac evaluates the IDs faster than text. Because of this, a pathname is converted to IDs, and the IDs are stored in the pz3 document. To find out the IDs of a specific folder, you can for example locate a texture map within this folder in Poser's Material Editor, then save the document, re-open it in a text editor, and inspect the textureMap lines.