---
id: object/codeunit/491
type: object
title: Codeunit 491 "Memory Mapped File"
summary: Codeunit 491 "Memory Mapped File" in Base Application (System.IO). 6 public procedures. Present since at least BC23, still in BC30.
tier: official
language: en
tags:
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  - base application
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    url: https://github.com/microsoft/BCApps/blob/ea08af5ef2d6a9b5c5af4a029288abbe2c883220/src/Layers/W1/BaseApp/System/MemoryMappedFile.Codeunit.al
    title: src/Layers/W1/BaseApp/System/MemoryMappedFile.Codeunit.al (releases/29.x)
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object_type: codeunit
object_id: 491
name: Memory Mapped File
namespace: System.IO
app: Base Application
extends: null
first_version: "23"
last_version: "30"
present_in:
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  - "24"
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---

# Codeunit 491 "Memory Mapped File"

> Codeunit 491 "Memory Mapped File" in Base Application (System.IO). 6 public procedures. Present since at least BC23, still in BC30.

Base Application · System.IO · BC23-30 · [source at ea08af5e](https://github.com/microsoft/BCApps/blob/ea08af5ef2d6a9b5c5af4a029288abbe2c883220/src/Layers/W1/BaseApp/System/MemoryMappedFile.Codeunit.al) · facts from BC29

## Procedures

- `CreateMemoryMappedFileFromTempBlob(var TempBlob: Codeunit "Temp Blob"; Name: Text)`
- `OpenMemoryMappedFile(Name: Text)`
- `ReadTextFromMemoryMappedFile(var Text: Text)`
- `ReadTextWithSeparatorsFromMemoryMappedFile(var Text: Text)`
- `GetName(): Text`
- `Dispose()`

## Triggers

OnRun

## Calls

From the extracted call graph of BC29 (graphify-al on the snapshot checkout): calls whose target is known from a declared type or an `Object::"Name"` argument. Interface dispatch and calls through events are not counted, so the list is not complete.

- [Codeunit 4100 "Temp Blob"](../codeunit/4100.md) (5 calls: `CreateMemoryMappedFileFromTempBlob → CreateInStream`, `CreateMemoryMappedFileFromTempBlob → HasValue`, `CreateMemoryMappedFileFromTempBlob → Length`, …)
- [Codeunit 10 "Type Helper"](../codeunit/10.md) (2 calls: `ReadTextWithSeparatorsFromMemoryMappedFile → LFSeparator`, `ReadTextWithSeparatorsFromMemoryMappedFile → ReadAsTextWithSeparator`)

## Called by

- [Codeunit 8626 "Config. Import Table in Backgr"](../codeunit/8626.md) (3 calls: `OnRun → Dispose`, `OnRun → OpenMemoryMappedFile`, `OnRun → ReadTextWithSeparatorsFromMemoryMappedFile`)

## Across versions

- Present in: BC23-30
- Changed (declaration) in: none

Source: AL metadata extracted from the code (names, ids, signatures, properties); no code bodies (D10).

## Ask your agent

Procedure bodies are not stored here (D10). The call sections above are our own, per object, from the BC29 call graph. For a procedure body or the calls of one procedure, ask bc-code-atlas (external, by Stefan Maron, MIT; default corpus w1-28), which the bc-observatory plugin connects: `bcatlas_resolve_node(object_type: "codeunit", object_name: "Memory Mapped File")`, then `bcatlas_get_procedure_body` or `bcatlas_get_neighbors` on the returned id.