Current documentation examples and tests generally use something like
to indicate that the container should go to sleep while waiting for exec calls in. While this works, it is rather obscure and ugly. Few users are likely to be immediately familiar with the ttyEnabled flag, and even then it is less than obvious why the interaction with cat would result in a container sleeping.
Better to use e.g.
which is self-explanatory. (GNU sleep accepts infinity as an argument, but POSIX does not specify it. POSIX does not seem to specify the d suffix either, but Busybox accepts it nonetheless. sleep 9999999 might be the most conservative choice.)
Better still to make this the default (if an image includes cat it probably includes sleep too) so users do not have to think about this technicality: