In emacs are any key sequences available for user macro bindings in all modes

I have recently started using org mode in emacs, but my macro bound in my initialisation file to C-x C-k T no longer works because this combination is used by outline mode which underpins org mode. I went by "Learning Gnu Emacs" by Debra Cameron et al. pub by O'Reilly, which states on page 160 that the sequences C-x C-k with 0-9 and A-Z are reserved for user macro bindings. This itself is contradicted, I have just noticed, on page 193, where, in outline mode, C-c C-k is bound to Show -> Show branches. So, please, are there any key sequences that are available still, and will be in all circumstances? I have left out the detail of my macro because it is irrelevant to this question. --- I have left the original question as it is to explain my mistake. Thanks to @Gilles I realise that I made a silly mistake in confusing C-c with C-x. The problem manifested itself in that using .org mode seemed to redefine my key bindings. This I have now resolved by using C-x instead of C-c . Macros bound to these still work in .org mode As to the question of what key sequence bindings are available, see: . This is part of an excellent and comprehensive set of articles on emacs by "Xah", available at: , and well worth the $15 he asks for them. This is almost an answer rather than an extension to my question. I have put it here to retain my acceptance of @Gilles earlier answer, and as it is too long for a comment