diff --git a/lib/spec.md b/lib/spec.md
index 6a23a35..7a4db79 100644
--- a/lib/spec.md
+++ b/lib/spec.md
@@ -8,7 +8,7 @@
 | `types`     | Commonly used types and aliases in submodules                                    |
 | `mem`       | Memory management for allocations, frees and copy operations                     |
 | `os`        | Abstractions for common tasks related to the operating system                    |
-| `io`        | Basic wrapper for general purpose input/output operations                        |
+| `io`        | Basic wrapper for general purpose synchronous input/output operations            |
 | `fs`        | File system operations extending functionality of the `io` module                |
 | `net`       | Module for networking capabilities                                               |
 | `vec`       | Vector data type implemented as growable array                                   |
@@ -16,6 +16,65 @@
 
 ## Bootstrap
 
-require dependency library in source
-    library name
-mark function as external library source
+This module contains sources required to boot a program, setup the runtime, libraries and eventually call the `main` function.
+Since only applications make use of this boot code it is of no use when compiling a library.
+It requires the `main` function to be defined. This function is the start of a gemstone applications and is called after setup with the following signature:
+```
+#[nomangle]
+fun main()
+```
+In contrast to other programming languages such as `C` the main function does not exit with a return value.
+In order to exit with a custom code use `std::os::exit()`.
+
+## Operating System (OS)
+
+## Memory management (mem)
+
+This module compiles function for generic memory mangement closely integrated with the host operating system.
+Included functionalities are: allocation, copy and clone operations.
+This module is built around the idea that memory mangement happens at byte level.
+Functions provided by this module are low-level functions for managing buffer of bytes without any considerations of higher abstractions of types.
+Thus most functions interact with the folloing unsigned 8-bit integral type:
+```
+type unsigned half half: u8
+```
+
+### Invalid memory and null pointer
+
+Gemstone has no pointers. References are conceptually no pointers but behave eqivalent on machine language level.
+In constrast to other languages the is no null. However since it is convention that a memory adress of zero is to be considered invalid gemstone will treat any reference of value zero as invalid reference.
+This property is used to check validity of references. It should be noted that this is not a fault prove method as the value of a reference can be changed at any point in time.
+The following example will set a refernce to a reference to "point" to adress 97:
+```
+ref float: myValue = (97 as i32) to ref float
+```
+
+### Allocation
+
+Buffers of bytes can be allocated by the operating system with the following `alloc` function:
+```
+fun ref u8:alloc(in u32: len)
+```
+This function allocates `len` bytes (as a buffers "length") and returns a reference to the buffer.
+The buffer is guaranted to be a consecutive field of bytes all initialized to zero.
+In case the allocations fails, for whatever reason, the returned reference will be zero (similar to `NULL` or `nullptr` in `C/C++`).
+Implementationwise this function should use the standard platforms way of allocating memory from the global processes heap.
+
+A block of memory allocated with `alloc` can be changed in length with `realloc`:
+```
+fun ref u8:realloc(in out ref u8: buf, in u32: len)
+```
+This function will reallocate an existing buffer (supplied by `buf`) to a new length and returns a reference to the buffer with the supplied length.
+Behaviorwise, the supplied reference to a preexisting buffer will be overwritten to the newly allocated buffer.
+The supplied reference and the returned result will be set to zero in case an error occurs.
+
+Memory can be given back to the operating system with the free function:
+```
+fun free(in out ref u8: buf)
+```
+This function will give back the memory block specified by `buf`.
+The reference supplied is the be considered invalid afterwards as it will be set to zero.
+
+## Input and Output (IO)
+
+## Networking (net)