diff --git a/Skills/Async.md b/Skills/Async.md
index 63e26c83..0143254f 100644
--- a/Skills/Async.md
+++ b/Skills/Async.md
@@ -1,7 +1,7 @@
 ## Asynchronous programming
 
 - Theory
-  - Event loop
+  - Event loop u
   - `try..catch`
   - Non-blocking
   - Async I/O
@@ -17,12 +17,12 @@
   - Dead locks
   - Live locks
   - Concurrent programming
-  - Parallel programming
+  - Parallel programming u
   - Actor Model
   - Thread
   - Process
 - Async contracts
-  - Callbacks
+  - Callbacks u
   - Callback-last-error-first
   - Thenable
   - Promise
diff --git a/Skills/Databases.md b/Skills/Databases.md
index c499feb1..247c3ec9 100644
--- a/Skills/Databases.md
+++ b/Skills/Databases.md
@@ -1,7 +1,7 @@
 ## Databases
 
 - Theory and concepts
-  - Data types
+  - Data types h
   - Performance tuning
   - Migrations
   - Schema versioning
@@ -31,7 +31,7 @@
   - Views
   - Subqueries
   - Stored procedures
-  - SQL functions
+  - SQL functions h
   - Materialized views
   - Replications
   - Virtualization
diff --git a/Skills/JavaScript.md b/Skills/JavaScript.md
index 0ff8fc89..69af117a 100644
--- a/Skills/JavaScript.md
+++ b/Skills/JavaScript.md
@@ -1,23 +1,23 @@
 ## JavaScript
 
 - Language
-  - `Object`
-  - `Function`
-  - `Boolean`
-  - `Number`
+  - `Object` u
+  - `Function` u
+  - `Boolean` u
+  - `Number` u
   - `BigInt`
   - `String`
   - `Symbol`
   - `Infinity`
-  - `NaN`
-  - `undefined`
-  - `null`
-  - `this`
+  - `NaN` u
+  - `undefined` u
+  - `null` u
+  - `this` u
   - `instanceof`
   - `...spread`
-  - `...rest`
-  - `typeof`
-  - Destructuring
+  - `...rest`u
+  - `typeof`u
+  - Destructuring u
   - Generators
   - Iterators
   - Async generator
@@ -36,7 +36,7 @@
   - Logical operators
   - Logical Assignment
   - Bitwise operators
-  - Ternary operator
+  - Ternary operator u
   - `void`
   - `yield`
   - `await`
@@ -59,27 +59,27 @@
   - Private class fields
   - Private class methods
 - Statements
-  - `if`
-  - `while`
-  - `do..while`
-  - `for`
+  - `if`u
+  - `while` u
+  - `do..while`u
+  - `for` u
   - `for..in`
-  - `for..of`
+  - `for..of` u
   - `for await`
-  - `throw`
-  - `break`
-  - `continue`
+  - `throw` u
+  - `break` u
+  - `continue` u
   - `import`
   - `export`
   - `label`
   - `try..catch`
-  - `switch`
-  - `class`
+  - `switch` u
+  - `class` k
   - `extends`
   - `with`
   - `new`
 - Functions
-  - Arrow function
+  - Arrow function u
   - Async function
   - Function declaration
   - Function expression
@@ -88,11 +88,11 @@
   - `Function.prototype.call`
   - `Function.prototype.bind`
   - `Function.prototype.apply`
-  - `return`
+  - `return` u
 - Data structures
-  - `Array`
-  - `Map`
-  - `Set`
+  - `Array` u
+  - `Map` u
+  - `Set` u
   - `WeakMap`
   - `WeakSet`
   - Typed arrays
@@ -102,16 +102,16 @@
   - `Proxy`
   - `RegExp`
   - `Date`
-  - `Math`
+  - `Math` u
   - `Reflect`
   - `Error`
   - `Atomics`
-  - `JSON`
+  - `JSON` k
   - `WeakRef`
   - `FinalizationRegistry`
   - `Intl`
   - `Promise`
-  - `console`
+  - `console` u
   - Timers
 - Infrastructure
   - V8
diff --git a/Skills/NodeJS.md b/Skills/NodeJS.md
index bd891457..4b0314e9 100644
--- a/Skills/NodeJS.md
+++ b/Skills/NodeJS.md
@@ -103,7 +103,7 @@
   - Inspector
 - Data access
   - Data access layer
-  - Repository
+  - Repository u
   - Active record
   - Query builder
   - Object-Relational Mapping
diff --git a/Skills/Paradigms.md b/Skills/Paradigms.md
index 91d5f7e5..829c0976 100644
--- a/Skills/Paradigms.md
+++ b/Skills/Paradigms.md
@@ -7,11 +7,11 @@
   - Non-structured programming
   - Functional programming
   - Prototype-based programming
-  - Object-oriented programming
+  - Object-oriented programming u
   - Object-based programming
   - Generic programming
   - Concurrent computing
-  - Asynchronous programming
+  - Asynchronous programming u
   - Parallel programming
   - Reactive programming
   - Functional-reactive (FRP)
@@ -30,8 +30,8 @@
   - Constructor
   - Operator `new`
   - Static method
-  - Method
-  - Async method
+  - Method h
+  - Async method h
   - Getters, Setters
   - Public fields
   - Private fields
diff --git a/Skills/Programming.md b/Skills/Programming.md
index e976b503..05899948 100644
--- a/Skills/Programming.md
+++ b/Skills/Programming.md
@@ -2,65 +2,65 @@
 
 - Concepts
   - Model
-  - Modeling
+  - Modeling k
   - Subject domain
-  - Algorithm
-  - Syntax
+  - Algorithm u
+  - Syntax u
   - Semantics
   - Abstraction
-  - Paradigm
-  - Programm
-  - Programming paradigm
-  - Programming language
+  - Paradigm h
+  - Programm u
+  - Programming paradigm h
+  - Programming language u
   - Contract
   - Module
-  - Library
+  - Library u
   - Package
   - Component
-  - Framework
-  - Platform
-  - Source code
+  - Framework u
+  - Platform u
+  - Source code u
   - Object code
   - Machine code
   - Microcode
-  - Software engineering
+  - Software engineering k
   - Decomposition
   - Control flow
   - Data flow
   - Code reuse
   - Defensive programming
-  - Don't repeat yourself (DRY)
-  - KISS principle
+  - Don't repeat yourself (DRY) h
+  - KISS principle h
 - Syntax and concepts
-  - Value
+  - Value h
   - Identifier
-  - Variable
-  - Constant
-  - Scalar
-  - Literal
-  - Expression
+  - Variable h
+  - Constant h
+  - Scalar k
+  - Literal u
+  - Expression u
   - Heap
-  - Function
+  - Function u
   - Procedure
-  - Method
-  - Class
+  - Method h
+  - Class h
   - Prototype
-  - Event
+  - Event u
   - Type
   - Flag
   - Lexical scope
-  - Code block
-  - Conditions
-  - Loops
-  - Assignment
+  - Code block u
+  - Conditions u
+  - Loops u
+  - Assignment u
   - Regular expression
   - Interface
   - Namespaces
   - Call stack
   - Naming conventions
   - Coding conventions
-  - Camel case
-  - Snake case
+  - Camel case u
+  - Snake case u
   - Kebab case
   - Trailing commas
   - Return early
@@ -81,9 +81,9 @@
   - Covariance
   - Contravariance
 - Functions
-  - Signature
-  - Argument
-  - Parameter
+  - Signature k
+  - Argument u
+  - Parameter u
   - Pure function
   - Lambda expression
   - Side effects
@@ -93,7 +93,7 @@
   - Higher order
   - Recursion
   - Tail call optimisation
-  - Callback
+  - Callback u
   - Listener
   - Composition
   - Pipe
@@ -105,31 +105,31 @@
   - Generator
   - Coroutine
 - Data structures
-  - Array
+  - Array u
   - Structure
   - Record
   - Enum
   - Instance
-  - Object
-  - Collection
-  - Set
+  - Object u
+  - Collection u
+  - Set u
   - Hash table
   - Linked list
   - Doubly list
   - Unrolled list
   - Circular list
-  - Queue
-  - Stack
+  - Queue k
+  - Stack k
   - Deque
-  - Tree
-  - Graph
-  - Iterator
+  - Tree h
+  - Graph h
+  - Iterator h
   - Mutable state
   - Immutable state
   - Serialization
   - String parsing
-  - JSON
-  - JSON5
+  - JSON u
+  - JSON5 h
   - YAML
 - Networking
   - DNS
@@ -142,7 +142,7 @@
   - URN
   - URI
 - Process and tools
-  - Compiler
+  - Compiler u
   - Just-in-time compilation
   - Ahead-of-time compilation
   - Transpiler
@@ -153,26 +153,26 @@
   - Dynamic linking
   - Static linking
   - Runtime
-  - Virtual machine
+  - Virtual machine u
   - Register-based VM
   - Stack-based VM
   - Containerization
-  - Debugger
+  - Debugger u
   - Tracing
   - Garbage collection
-  - Refactoring
-  - Code review
+  - Refactoring u
+  - Code review h
   - Exception
   - Unittesting
-  - git
-  - Github
+  - git u
+  - Github u
   - Docker
   - Kubernetes
   - GCC
   - LLVM
 - Antipatterns
   - Magic numbers
-  - Hard code
+  - Hard code h
   - Soft code
   - Cryptic code
   - Improbability factor
@@ -193,7 +193,7 @@
   - Too many parameters
   - Pass-through parameters
   - Accumulate and fire
-  - Use switch/case
+  - Use switch/case u
   - Temporary field
   - Handle object as instances and hashes at the same time
   - Use fields instead of arguments
@@ -214,11 +214,11 @@
   - Ring
   - Virtual memory
   - File system
-  - Linux
+  - Linux u
   - Unix
   - BSD
   - MacOS
-  - Windows
+  - Windows u
   - Real-time OS
   - Embedded OS
 - Standards
@@ -234,6 +234,6 @@
   - ISO
   - MIME
   - OWASP
-  - UTF-8
+  - UTF-8 u
   - W3C
   - ODMG