BIP93: correct threshold range

bip-0093.mediawiki

@@ -67,8 +67,8 @@ It reuses the base-32 character set from BIP-0173, and consists of:
 * A human-readable part, which is the string "ms" (or "MS").
 * A separator, which is always "1".
 * A data part which is in turn subdivided into:
-** A threshold parameter, which MUST be a single digit between "2" and "9", or the digit "0".
-*** If the threshold parameter is "0" then the share index, defined below, MUST have a value of "s" (or "S").
+** A threshold digit (also called ''k'' in the codex book), which MUST be a single digit between "2" and "9", or the digit "0". For shared secrets, this digit encodes the threshold (the number of shares required for recovery): thresholds 2-9 are encoded as digits "2"-"9" respectively. For unshared secrets, threshold 1 is denoted by the share index "s" (not by the threshold digit); the digit "0" is recommended for the threshold digit in this case, but any digit is allowed as it is ignored.
+*** If the threshold digit is "0" then the share index, defined below, MUST have a value of "s" (or "S").
 ** An identifier consisting of 4 bech32 characters.
 ** A share index, which is any bech32 character. Note that a share index value of "s" (or "S") is special and denotes the unshared secret (see section "Unshared Secret").
 ** A payload which is a sequence of up to 74 bech32 characters. (However, see '''Long codex32 Strings''' below for an exception to this limit.)
@@ -146,14 +146,14 @@ The master seed is decoded by converting the payload to bytes:
 
 Note that unlike the decoding process in BIP-0173, we do NOT require that the incomplete group be all zeros.
 
-For an unshared secret, the threshold parameter (the first character of the data part) is ignored (beyond the fact it must be a digit for the codex32 string to be valid).
-We recommend using the digit "0" for the threshold parameter in this case.
+For an unshared secret, the threshold digit (the first character of the data part) is ignored (beyond the fact it must be a digit for the codex32 string to be valid).
+We recommend using the digit "0" for the threshold digit in this case. Note that threshold 1 is denoted by the share index "s", not by the threshold digit.
 The 4 character identifier also has no effect beyond aiding users in distinguishing between multiple different master seeds in cases where they have more than one.
 
 ===Recovering Master Seed===
 
 When the share index of a valid codex32 string (converted to lowercase) is not the letter "s", we call the string an codex32 share.
-The first character of the data part indicates the threshold of the share, and it is required to be a non-"0" digit.
+The first character of the data part is the threshold digit, which encodes the threshold (the number of shares required for recovery). For a codex32 share, the threshold digit is required to be a non-"0" digit (i.e., "2" through "9"), encoding thresholds 2 through 9 respectively.
 
 In order to recover a master seed, one needs a set of valid codex32 shares such that: