First and more importantly (bad grammar is so irksome, isn’t it?), it’s “toe the line”. Don’t confuse it with nautical tow lines…it’s about feet. The phrase originated with soldiers lining up in the military or runners in track and field events, where officials would call out “Toe the line!” to get the runners ready. Either way, it’s the digits of the feet, lined up in a row, like this:
Although I’m glad to talk about this little phraseological pet peeve of mine, not many people ask me about it, but many DO ask me about the other toe line: The area under a sink or other element that provides space for a wheelchair rider’s toes and foot rests. Here’s the toe clearance diagram from the Americans with Disabilities Act (ADA) and California Building Code (CBC):
Here’s a diagram that’s more helpful for thinking about the turning space. Imagine this pile of forms sliding in and out of a restroom, kitchen, work areas, etc. That’s where the 9 inch high, 6" maximum depth toe space (and the corresponding 27” maximum knee space height) should be applied.
“Space extending greater than 6 inches (152 mm) beyond the available knee clearance at 9 inches (229 mm) above the finish floor or ground shall not be considered toe clearance.”
This says "available" knee clearance. In my opinion, if you don't have an obstruction limiting the knee clearance, you can claim more than 6" of horizontal toe clearance.
Bonus Tip: A lavatory is not a sink…
A related confusion is that the CBC differs from the ADA in sinks. We have these two definitions (Chapter 2) in California:
LAVATORY. A fixed bowl or basin with running water and drainpipe, as in a toilet or bathing facility, for washing or bathing purposes. (As differentiated from the definition of “Sink”.)
SINK. A fixed bowl or basin with running water and drainpipe, as in a kitchen or laundry, for washing dishes, clothing, etc. (As differentiated from the definition of “Lavatory”.)
So whereas kitchen sinks and work counters need to have the clearances shown above, a bathroom lavatory in California needs a thinner front edge, to allow for more ability to get in nice and close. To remember this, picture someone in a wheelchair washing their face in the bathroom - they need to get in closer than when they’re reaching out and washing dishes in a kitchen sink.
Duravit, Wet Style, and Barclay have California-complying sinks, and with great contemporary designs to boot (including some by Philippe Starck), and many have drains in the very rear, which is a plus for added knee space:
As I always say, we should take any opportunity to provide MORE space than the code minimums require. If you can provide more knee space, then someone in an electric wheelchair with a joystick out front, or someone in a high-seated scooter who pulls up sideways and needs more knee space when they turn their seat 90 degrees is going to thank you. Who knows - that might just be you or a family member one day. So let’s make better, more flexible architecture…and not just toe the line.