@noisy just to increase a little the accuracy there, not that this will make any difference on the didactical effects of your post.
The value you showed and suggested similar characters were omitted, in the very case of Steem, it's encoded as Base58.
Base58
Base58 is the same as Base64, excluding:
0(zero)O(capitalo)I(capitali)l(lower casel)+(plus sign)/(slash)
This means, that 6 characters from the original Base64 are not used to prevent confusion: (64 - 6 = 58)
So the tip here is that lower case i and lower case o are included, just not their similar pairs.
For usages outside the Steem world, some people adopt the Base56, which consists of the same rules as Base58, but also removing two more digits, the number one (1) and the lower case o
Base58-Check
N-O-T the one used by Steem, but for those curious on binary encoding, give it a check, since the implementation may vary from an app to another, the Base58 check is able to include, it's version at the beginning and a checksum value at the end, to ensure you did not misplaced a given character while copying it out.