This followed the publishing of continuously numbered postcards of European cities and artist-signed postcards such as that of the painter Carl Wuttke with motifs from Egypt.

The series starting with 15001 is of Constantinople. The letters after the series numbers represent the postcard style. There are four basic styles:

• e - Landscape with smaller picture anchored to top left with 1/4 writing area on the right and bottom or full page picture with a square writing area on right bottom or top left corners
• g - Landscape with bottom 1/4 to 1/3 reserved for writing
• h - Portrait with bottom 1/4 to 1/3 reserved for writing
• s - Landscape with right 1/4 reserved for writing

Sometimes this letter is preceded with a, B, C, G or S.

The cards with series numbers ending in "12", "15", "45" and "85" use a different font type.