Docs: Mention "remapping" for dates exceeding era year

Ref tc39#2865

docs/plaindate.md

@@ -81,8 +81,8 @@ If the string isn't valid according to ISO 8601, then a `RangeError` will be thr
 
 The `overflow` option works as follows, if `item` is an object:
 
-- In `constrain` mode (the default), any out-of-range values are clamped to the nearest in-range value.
-- In `reject` mode, the presence of out-of-range values will cause the function to throw a `RangeError`.
+- In `constrain` mode (the default), any out-of-range values are clamped to the nearest in-range value (after assuming extension of eras over arbitrary years to substitute `era` and `eraYear` with appropriate values for the `item`).
+- In `reject` mode, the presence of out-of-range values (after assuming extension of eras over arbitrary years to substitute `era` and `eraYear` with appropriate values for the `item`) will cause the function to throw a `RangeError`.
 
 The `overflow` option is ignored if `item` is a string.
 

docs/plaindatetime.md

@@ -112,8 +112,8 @@ If the string isn't valid according to ISO 8601, then a `RangeError` will be thr
 
 The `overflow` option works as follows, if `item` is an object:
 
-- In `constrain` mode (the default), any out-of-range values are clamped to the nearest in-range value.
-- In `reject` mode, the presence of out-of-range values will cause the function to throw a `RangeError`.
+- In `constrain` mode (the default), any out-of-range values are clamped to the nearest in-range value (after assuming extension of eras over arbitrary years to substitute `era` and `eraYear` with appropriate values for the `item`).
+- In `reject` mode, the presence of out-of-range values (after assuming extension of eras over arbitrary years to substitute `era` and `eraYear` with appropriate values for the `item`) will cause the function to throw a `RangeError`.
 
 The `overflow` option is ignored if `item` is a string.
 

docs/plainyearmonth.md

@@ -83,8 +83,8 @@ A `RangeError` will also be thrown for strings that contain a `Z` in place of a
 
 The `overflow` option works as follows, if `item` is an object:
 
-- In `constrain` mode (the default), any out-of-range values are clamped to the nearest in-range value.
-- In `reject` mode, the presence of out-of-range values will cause the function to throw a `RangeError`.
+- In `constrain` mode (the default), any out-of-range values are clamped to the nearest in-range value (after assuming extension of eras over arbitrary years to substitute `era` and `eraYear` with appropriate values for the `item`).
+- In `reject` mode, the presence of out-of-range values (after assuming extension of eras over arbitrary years to substitute `era` and `eraYear` with appropriate values for the `item`) will cause the function to throw a `RangeError`.
 
 The `overflow` option is ignored if `item` is a string.
 

docs/zoneddatetime.md

@@ -175,8 +175,8 @@ Instead of using `Temporal.ZonedDateTime` with an offset time zone, it may be ea
 
 The `overflow` option works as follows, if `item` is an object:
 
-- In `'constrain'` mode (the default), any out-of-range values are clamped to the nearest in-range value.
-- In `'reject'` mode, the presence of out-of-range values will cause the function to throw a `RangeError`.
+- In `'constrain'` mode (the default), any out-of-range values are clamped to the nearest in-range value (after assuming extension of eras over arbitrary years to substitute `era` and `eraYear` with appropriate values for the `item`).
+- In `'reject'` mode, the presence of out-of-range values (after assuming extension of eras over arbitrary years to substitute `era` and `eraYear` with appropriate values for the `item`) will cause the function to throw a `RangeError`.
 
 The `overflow` option is ignored if `item` is a string.