List of Hidden Characters (“What is that weird character in my text?”)
I've been importing copy from Quark files into InDesign CS3 and I keep getting odd hidden characters at the beginning of my paragraphs. The symbol looks like a colon, but it's a hidden characters, so it's shows up the same color as whatever layer it is on.
I looked for a "decoder ring" that lists of all the hidden characters in InDesign, but couldn't find one! Frustrated, I compiled my own list and published it in the most recent edition of InDesign Magazine (Issue 19, August/September, 2007). If you're not currently a subscriber, I encourage you to take this opportunity to subscribe. Remember that InDesignSecrets readers can get a discount.
These invisible characters (such as returns, spaces, tabs, and so on) only appear when you have Type > Show Hidden Characters turned on. And, as you pointed out, they take on the color of their layer (just like the frame edges of selected objects).
Here's a sampling of some of the most common characters from that article: