diff --git a/packages/core/src/lib/markdown-it/highlight/HighlightRuleComponent.ts b/packages/core/src/lib/markdown-it/highlight/HighlightRuleComponent.ts
index 7ddc47a10..67ee973af 100644
--- a/packages/core/src/lib/markdown-it/highlight/HighlightRuleComponent.ts
+++ b/packages/core/src/lib/markdown-it/highlight/HighlightRuleComponent.ts
@@ -1,6 +1,6 @@
 import { splitCodeAndIndentation } from './helper';
 
-const LINESLICE_CHAR_REGEX = /(_?)(\d+)\[(\d*):(\d*)]/;
+const LINESLICE_CHAR_REGEX = /(\+?)(\d+)\[(\d*):(\d*)]/;
 const LINESLICE_WORD_REGEX = /(\d+)\[(\d*)::(\d*)]/;
 const LINEPART_REGEX = /(\d+)\[(["'])((?:\\.|[^\\])*?)\2]/;
 const UNBOUNDED = -1;
@@ -43,13 +43,13 @@ export class HighlightRuleComponent {
     const linesliceWordMatch = compString.match(LINESLICE_WORD_REGEX);
     const sliceMatch = linesliceCharMatch || linesliceWordMatch;
     if (sliceMatch) {
-      // There are four/five capturing groups: [full match, is highlight spaces (for char slice),
+      // There are four/five capturing groups: [full match, is absolute indexing (for char match),
       //                                        line number, start bound, end bound]
       const groups = sliceMatch.slice(1); // discard full match
 
-      let isHighlightSpaces = false;
+      let isAbsoluteIndexing = false;
       if (sliceMatch === linesliceCharMatch) {
-        isHighlightSpaces = groups.shift() === '_';
+        isAbsoluteIndexing = groups.shift() === '+';
       }
 
       const lineNumber = HighlightRuleComponent
@@ -65,7 +65,7 @@ export class HighlightRuleComponent {
       let bound = groups.map(x => (x !== '' ? parseInt(x, 10) : UNBOUNDED)) as [number, number];
       const isCharSlice = sliceMatch === linesliceCharMatch;
       bound = isCharSlice
-        ? HighlightRuleComponent.computeCharBounds(bound, lines[lineNumber - 1], isHighlightSpaces)
+        ? HighlightRuleComponent.computeCharBounds(bound, lines[lineNumber - 1], isAbsoluteIndexing)
         : HighlightRuleComponent.computeWordBounds(bound, lines[lineNumber - 1]);
 
       return new HighlightRuleComponent(lineNumber, true, [bound]);
@@ -102,26 +102,25 @@ export class HighlightRuleComponent {
    * comparing the bounds and the line's range.
    *
    * If the bound does not specify either the start or the end bound, the computed bound will default
-   * to the start or end of line. The bound will either include or exclude leading whitespaces depending
-   * on the user's preference.
+   * to the start or end of line. The bound can be either absolute or relative to the indentation level.
    *
    * @param bound The user-defined bound
    * @param line The given line
-   * @param isHighlightSpaces Whether to highlight leading whitespaces
+   * @param isAbsoluteIndexing Whether the bound is absolute or relative to the indentation level
    * @returns {[number, number]} The actual bound computed
    */
   static computeCharBounds(bound: [number, number], line: string,
-                           isHighlightSpaces: boolean): [number, number] {
+                           isAbsoluteIndexing: boolean): [number, number] {
     const [indents] = splitCodeAndIndentation(line);
     let [start, end] = bound;
 
     if (start === UNBOUNDED) {
-      if (isHighlightSpaces) {
+      if (isAbsoluteIndexing) {
         start = 0;
       } else {
         start = indents.length;
       }
-    } else if (!isHighlightSpaces) {
+    } else if (!isAbsoluteIndexing) {
       start += indents.length;
       // Clamp values
       if (start < indents.length) {
@@ -135,7 +134,7 @@ export class HighlightRuleComponent {
 
     if (end === UNBOUNDED) {
       end = line.length;
-    } else if (!isHighlightSpaces) {
+    } else if (!isAbsoluteIndexing) {
       end += indents.length;
 
       // Clamp values
diff --git a/packages/core/test/unit/lib/markdown-it/highlight/HighlightRuleComponent.test.ts b/packages/core/test/unit/lib/markdown-it/highlight/HighlightRuleComponent.test.ts
index 0a17b159a..12e5eef6e 100644
--- a/packages/core/test/unit/lib/markdown-it/highlight/HighlightRuleComponent.test.ts
+++ b/packages/core/test/unit/lib/markdown-it/highlight/HighlightRuleComponent.test.ts
@@ -44,7 +44,7 @@ describe('parseRuleComponent', () => {
   });
 });
 
-describe('computeCharBounds, no whitespace highlighting', () => {
+describe('computeCharBounds, relative to indent-level', () => {
   test('computes character bounds correctly', () => {
     const bounds = HighlightRuleComponent.computeCharBounds([2, 5], '  some text', false);
     expect(bounds).toEqual([4, 7]);
@@ -66,7 +66,7 @@ describe('computeCharBounds, no whitespace highlighting', () => {
   });
 });
 
-describe('computeCharBounds, with whitespace highlighting', () => {
+describe('computeCharBounds, absolute value bounds', () => {
   test('computes character bounds correctly', () => {
     const bounds = HighlightRuleComponent.computeCharBounds([2, 5], '  some text', true);
     expect(bounds).toEqual([2, 5]);