It gets a little hard here - what are the legal times? Is there always a "-" in between? What are some examples for invalid times?

For example,
"7:00" alone should be invalid since it doesn't have an ending time
"9am to 4pm" should be valid, but doesn't have a "-"
"09:00-17:00" should be valid

etc... Or just check for presence of "humantime" and that's it?