diff --git a/.gitignore b/.gitignore
index bade31f..d64610c 100644
--- a/.gitignore
+++ b/.gitignore
@@ -17,3 +17,4 @@
 /d4rt_formulas.iml
 .aider*
 .build-container-cache
+/coverage/
diff --git a/CLAUDE.md b/CLAUDE.md
index e2d61c3..00d0338 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -8,6 +8,6 @@
 - Examples:
   - `flutter pub get` --> `./flutterw pub get`
   - `flutter run -d linux` --> `./flutterw run -d linux`
-- See `./Makefile` for more use examples.
+- See `./Makefile` for more examples.
 
 
diff --git a/TODO.md b/TODO.md
new file mode 100644
index 0000000..f359411
--- /dev/null
+++ b/TODO.md
@@ -0,0 +1,22 @@
+[ ] Means not done
+[x] Means done
+
+- [ ] Unify error reporting. Create class ErrorHandler that get notified of every catched exception. This class prints the exception in stdout.
+- Refactor formula and unit loading:
+  - [ ] Create method `List<Object?> parseD4rtLiteral(String arrayStringLiteral). It parses a d4rt array literal (containing maps and arrays) to a List<Object?> using d4rt
+  - [ ] Remove `fromArrayStringLiteral` from UnitSpec and Formula.
+  - [ ] Create function `List<Object> parseCorpusElements(String arrayStringLiteral)`. It uses parseD4rtLiteral and determines if each element of the array is a formula or a unit. Then converts the objects with Formula.fromSet or UnitSpec.fromSet.
+  - [ ] Create method loadFormulaElements( List<Object> elements). Tipically receives the list from parseCorpusElements(). It loads the units first, then the formulas, to avoid missing dependencies.
+- [ ] Use a single table in database `FORMULAELEMENT` to store formulas and units. The table contains only two columns: autonumeric id and text.
+- [ ] Create Formula.toStringLiteral. It is the reverse of Formula.fromSet( Formula.fromArrayStringLiteral(string)[0] )
+- [ ] Create UnitSpec.toStringLiteral, like Formula.toStringLiteral
+- Database file location:
+  - [ ] In linux, the sqlite database file will be located following rules at https://specifications.freedesktop.org/basedir/latest/
+  - [ ] In Windows, the sqlite database file will be in %appdata%/Roaming
+  - [ ] In Macos, the sqlite database file will be in ~/Library/Application Support
+- [ ] Initialize database at startup
+  - [ ] If the database is empty, sugest to use a default corpus
+  - [ ] If the user choose to use the default corpus, populate de database with the default corpus (load defaultcorpus, and the use toStringLiteral)
+  - [ ] From now on, the corpus will be loaded from database instead of assets
+- [ ] Create method List<UnitSpec> Corpus.withDependencies(Formula formula). It will return the list of units of the formula, and related units from the corpus.
+- [ ] Add a Share button to the formula list. It will export the array string literal of the formula with the units from Corpus.withDependencies().