clarify text situation, only three ranks

1 files changed, 31 insertions, 25 deletions

diff --git a/rprt.md b/rprt.md
index 9878bf9..8921935 100644
--- a/rprt.md
+++ b/rprt.md
@@ -8,18 +8,25 @@ A compositional, point-free language for text manipulation.
 
 All functions work with two core types:
 
-1. **Selection** — addresses and regions in buffers
+1. **Selection** - addresses and regions in buffers
 
-   Every selection exists within one or more buffers. Selections have a rank:
+Every selection exists within one or more buffers. Selections have a rank:
 
-   - **Rank 0**: Position — a natural number offset within a single buffer
-   - **Rank 1**: Range — a pair of positions `[start, end)` with capture groups, within a single buffer
-   - **Rank 2**: Ranges — a list of ranges with capture groups, within a single buffer
-   - **Rank 3**: Multi-buffer selection — a mapping from buffer identifiers to rank 2 selections
+- **Rank 0**: Position - a natural number offset within a single buffer
+- **Rank 1**: Range - a pair of positions `[start, end)` with capture groups, within a single buffer
+- **Rank 2**: Ranges - a list of ranges with capture groups, within a single buffer
+- **Rank 3**: Multi-buffer selection - a mapping from buffer identifiers to rank 2 selections
 
-   Ranks 0-2 operate within a single buffer (typically the current buffer). Rank 3 is distinguished by spanning multiple buffers simultaneously.
+Ranks 0-2 operate within a single buffer (typically the current buffer). Rank 3 is distinguished by spanning multiple buffers simultaneously.
 
-2. **Text** — string data
+2. **Text** - string data
+
+Text has three ranks:
+- **Rank 1**: A single string
+- **Rank 2**: A list of strings
+- **Rank 3**: A mapping from buffer identifiers to lists of strings
+
+Unlike Selection, Text has no meaningful need to distinguish rank 0: a single character is simply a rank 1 string of length one.
 
 ### Function Types
 
@@ -33,12 +40,12 @@ Following APL conventions, functions may have nullary, monadic, and dyadic forms
 
 When a Text argument is required, a Selection is implicitly coerced to Text by extracting its contents. This coercion has no side effects.
 
-| Input rank | Coerced Text                                      |
-|------------|---------------------------------------------------|
-| 0          | Empty string (position has no extent)             |
-| 1          | Contents of the range                             |
-| 2          | Contents of each range (multiple text values)     |
-| 3          | Contents per buffer per range (multiple values)   |
+| Input rank | Coerced Text                                                          |
+|------------|-----------------------------------------------------------------------|
+| 0          | The character at that position, or empty string at end of buffer      |
+| 1          | Contents of the range                                                 |
+| 2          | Contents of each range (multiple text values)                         |
+| 3          | Contents per buffer per range (multiple values)                       |
 
 For ranks 2 and 3, the selection provides multiple text values. Text functions pair these values with selection ranges following the broadcasting rules in §1.2.
 
@@ -226,18 +233,18 @@ In the niladic form this is `(.) /re/` (left hook semantics §1.2, or left assoc
 Operators take functions as arguments and return new functions. Selection function operators fall into two categories which compose in a restricted manner:
 
 **Search Modifiers** (at most one allowed):
-- _(none)_ — Unmodified search semantics (see §2.1)
-- `'` — Reverse (§2.2.2)
-- `;` — Sequential (§2.2.3)
-- `';` — Reverse-Sequential
-- `;'` — Sequential-Reverse
+- _(none)_ - Unmodified search semantics (see §2.1)
+- `'` - Reverse (§2.2.2)
+- `;` - Sequential (§2.2.3)
+- `';` - Reverse-Sequential
+- `;'` - Sequential-Reverse
 
 **Result Transformations** (at most one allowed):
-- _(none)_ — Unmodified result
-- `~` — Complement (§2.2.4)
-- `?` — Conditional (§2.2.5)
-- `~?` — Complement-Conditional
-- `?~` — Conditional-Complement
+- _(none)_ - Unmodified result
+- `~` - Complement (§2.2.4)
+- `?` - Conditional (§2.2.5)
+- `~?` - Complement-Conditional
+- `?~` - Conditional-Complement
 
 A fully-specified selection function has the form:
 
@@ -380,7 +387,6 @@ Text operations follow the broadcasting rules described in §1.2. When the text
 | `τ \|`   | Run `τ`                                          | Return selection of ephemeral buffer output |
 
 **Note:** The text argument `τ` may be a string literal or a Selection (which coerces to Text).
-**Note:** `\|` and `d` are undefined when the rank of `τ` is 0.
 
 | Function | Effect                                               | Semantics                                                 |
 |----------|------------------------------------------------------|-----------------------------------------------------------|